{"found":57709,"hits":[{"document":{"authors":[{"affiliation":[{"name":"University of Wroc\u0142aw, Chemistry"}],"contributor_roles":[],"family":"Janeta","given":"Mateusz","url":"https://orcid.org/0000-0003-2197-7913"}],"blog":{"authors":null,"community_id":"c21eed24-c860-43d0-997c-0bc782922544","created":1788652800,"current_feed_url":null,"description":null,"doi":"https://doi.org/10.59350/silsesquioxane","favicon":"https://rogue-scholar.org/api/communities/c21eed24-c860-43d0-997c-0bc782922544/logo","feed_format":"application/atom+xml","feed_url":"https://silsesquioxane.blogspot.com/feeds/posts/default","filter":null,"generator":"Blogger","home_page_url":"https://silsesquioxane.blogspot.com/","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"silsesquioxane","status":"active","subfield":"1604","title":"Polyhedral Oligomeric Silsesquioxane (POSS) Chemistry","updated":1791045034,"use_api":true},"blog_name":"Polyhedral Oligomeric Silsesquioxane (POSS) Chemistry","blog_slug":"silsesquioxane","content_html":"

Epoxy nanocomposite vitrimers containing polyhedral oligomeric silsesquioxane (POSS) were reported by Hongkun Yang, Changfei He, Thomas P. Russell, and Dong Wang in Giant in 2020. Studies devoted specifically to POSS in vitrimer networks remain scarce, and this one still carries the subject almost on its own. Glycidyl POSS was incorporated as a nanoscale filler into a transesterification-based epoxy, raising tensile strength and strain at break simultaneously while shifting the topology-freezing transition upward by more than 36 \u00b0C. A handful of related reports place silsesquioxane particles in other dynamic matrices, among them the bio-based polymethacrylate vitrimer nanocomposites of Hajiali, Tajbakhsh, and Mari\u0107, and in every case the cage serves as reinforcing filler.

Key findings at a glance
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Over the same period the silicon\u2013oxygen bond has become one of the most productive dynamic covalent motifs in vitrimer design, through TBD-catalyzed siloxane exchange from the Du Prez group and through direct silyl ether metathesis discovered in the Guan laboratory. The two routes act on different bonds, Si\u2013O\u2013Si in the first case and Si\u2013O\u2013C in the second. The T8 silsesquioxane cage is built from twelve Si\u2013O\u2013Si bridges, structurally the same linkage that the Du Prez system exchanges in under six seconds, yet the question of whether those bridges can act as the dynamic site, rather than as inert structural scaffolding, appears not to have been put. What follows sets out what is established across five studies and identifies the control experiment that would settle the question.

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Associative vs Dissociative Covalent Adaptable Networks: What Defines a Vitrimer

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Covalent adaptable networks divide into two families, and the distinction governs everything that follows. In a dissociative mechanism the crosslink breaks before a new bond forms, so the crosslink density falls transiently, the viscosity drops sharply, and at sufficiently high temperature the network can depolymerize outright. The reversible Diels\u2013Alder reaction is the canonical example. In an associative mechanism the incoming partner binds before the original bond is cleaved, so the number of crosslinks remains constant across the entire temperature range. The material rearranges its topology without ever losing network integrity, and it was this class that Ludwik Leibler named vitrimers in 2011, in the work by Damien Montarnal and co-workers that established silica-like malleability in a permanent organic network.

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\"POSS
Fig. 1. Two families of covalent adaptable networks. In the dissociative mechanism (a) the crosslink is cleaved first, which lowers the crosslink density transiently and, in the limit, costs the network its integrity. In the associative mechanism (b) the exchange partner adds before the original bond breaks, by way of the transition state marked with a dotted circle, so the number of junctions stays constant. Vitrimers belong exclusively to the second group. Redrawn from: Denissen, W.; Winne, J. M.; Du Prez, F. E. Chem. Sci. 2016, 7, 30. DOI: 10.1039/C5SC02223A, Fig. 1.
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Arrhenius Flow and the Topology-Freezing Transition (Tv) of Vitrimers

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The rheological consequence of associative exchange is best seen on an Angell fragility plot. Thermoplastics possess a narrow glass transition across which the viscosity collapses by orders of magnitude within a few tens of degrees, which in practice means a narrow processing window and a requirement for close temperature control. Vitrimers behave differently: their viscosity follows an Arrhenius law over a very wide temperature range, in the manner of silica rather than polystyrene. In rheological terminology they are strong liquids, and the practical consequence is a material that can be shaped with the tolerance of a silicate glass rather than the precision demanded by a thermoplastic melt.

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\"Angell
Fig. 2. Angell fragility plot. Thermoplastics (PS, PVC) show the steep, almost vertical viscosity collapse characteristic of fragile liquids. The epoxy\u2013POSS vitrimers fall along a straight line, as silica does, indicating Arrhenius flow and a broad processing window. Their fragility indices are 13 for the unfilled network and 16 at 10 wt% POSS, both below the value of roughly 20 for SiO\u2082. Vitrimer points were calculated from the Ea and Tv values in Yang, H.; He, C.; Russell, T. P.; Wang, D. Giant 2020, 4, 100035, Table 2. DOI: 10.1016/j.giant.2020.100035; reference curves were generated with the MYEGA model of Mauro, J. C.; Yue, Y.; Ellison, A. J.; Gupta, P. K.; Allan, D. C. Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 19780. DOI: 10.1073/pnas.0911705106.
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The temperature at which the viscosity passes 10\u00b9\u00b2 Pa\u00b7s defines the topology-freezing transition, Tv. Above it the network is a viscoelastic liquid with a fixed junction count; below it the material is an elastomer or a glass. Together with Tg this provides two independent handles on the mechanical response, and much of the interest in filled vitrimers comes from the possibility of moving one without moving the other.

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Synthesis of Functionalized POSS Cages: Condensation, Corner Capping, Hydrosilylation

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Any discussion of POSS in dynamic networks has to begin with how the cages are made, because the available substitution patterns determine what network architectures are reachable. The cubic T8 framework, Si\u2088O\u2081\u2082R\u2088, forms by hydrolytic condensation of a trifunctional silane RSiX\u2083 where X is chloride or alkoxide. The reaction is run in dilute solution, often for days, and for many R groups the closed cubic cage is the thermodynamic sink, so the process is self-correcting if given enough time. Yields are strongly substituent-dependent, and the same conditions that deliver a clean octamer for one R group can give a mixture of T8, T10, and T12 cages for another. Octa(3-aminopropyl)silsesquioxane, the building block behind much of the functional POSS work from the University of Wroc\u0142aw, is obtained this way from 3-aminopropyltriethoxysilane and then elaborated by amide coupling at the eight peripheral amines.

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Two further routes matter for network chemistry. Corner capping starts from an incompletely condensed trisilanol, R\u2087Si\u2087O\u2089(OH)\u2083, and closes the eighth vertex with a different RSiCl\u2083, which gives a cage bearing seven of one substituent and one of another. This is the standard way to make a monofunctional POSS for pendant attachment. Platinum-catalyzed hydrosilylation of octahydridosilsesquioxane, Si\u2088O\u2081\u2082H\u2088, with a terminal alkene gives octa-substituted cages directly and tolerates a wide range of functionality, which is how the glycidyl cages used in vitrimer work are most conveniently accessed. Octaglycidyl cages are most reliably prepared by hydrosilylation of Si\u2088O\u2081\u2082H\u2088 with allyl glycidyl ether, since the direct hydrolytic condensation of (3-glycidoxypropyl)trimethoxysilane is complicated by the sensitivity of the oxirane ring to the acid or base used to promote condensation. Commercial glycidyl POSS is supplied in some grades as a cage mixture rather than a pure octamer, so the stoichiometry is worth checking in any given batch. Yang and co-workers used material from Hybrid Plastics and report a molar mass of 1337.88 g/mol with an epoxy equivalent weight of 167. Those values match the calculated mass of Si\u2088O\u2081\u2082(C\u2086H\u2081\u2081O\u2082)\u2088 at 1337.9 g/mol and one eighth of it at 167.2, so their material corresponds to full octa-substitution of a T8 cage.

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The same Karstedt hydrosilylation chemistry appears again in the silicone vitrimer discussed later in this post, where allyl glycidyl ether is added across the two Si\u2013H bonds of 1,1,3,3-tetramethyldisiloxane to give a difunctional siloxane epoxide. What matters for the argument developed here is that none of this requires new synthetic methodology. Every cage and every linker involved is either commercial or accessible in one step from commercial material, which means the experiment proposed at the end of this post can be attempted immediately.

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Epoxy\u2013POSS Nanocomposite Vitrimers by Hydroxyl\u2013Ester Transesterification

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The only dedicated POSS vitrimer study uses a formulation assembled entirely from catalogue reagents. Yang and co-workers combined diglycidyl ether of bisphenol A (DER 332), dodecanedioic acid as the hardener, and glycidyl POSS, with 1,5,7-triazabicyclo[4.4.0]dec-5-ene at 2.5 mol% relative to carboxyl groups as the transesterification catalyst. The components were heated to 160 \u00b0C with stirring, the catalyst was added, and the homogeneous melt was poured into preheated PTFE molds and cured for six hours at 160 \u00b0C. POSS was introduced at 2, 5, 8, and 10 wt%, with the DGEBA fraction adjusted each time to hold the epoxy to carboxyl stoichiometry at unity. The low viscosity of glycidyl POSS and its miscibility with DGEBA make this a genuinely homogeneous system rather than a dispersion, which matters because aggregation is the usual failure mode for silica-type fillers in epoxy networks.

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The exchange chemistry is hydroxyl\u2013ester transesterification. Secondary hydroxyl groups generated by epoxide ring opening attack ester linkages elsewhere in the network, transferring a junction without changing the total number of junctions. Infrared spectroscopy confirmed essentially complete conversion: the epoxide bands of DGEBA at 915 cm\u207b\u00b9 and of POSS at 909 and 1199 cm\u207b\u00b9 disappeared, while the ester carbonyl appeared at 1737 cm\u207b\u00b9. Swelling in chlorobenzene for 72 hours left every sample insoluble, with gel fractions rising from 97.12% for the unfilled network to 98.06% at 10 wt% POSS and crosslink densities increasing from 7.04 to 10.6 \u00d7 10\u207b\u2074 mol cm\u207b\u00b3.

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\"Synthesis
Fig. 3. Construction of the epoxy\u2013POSS nanocomposite vitrimer. The upper panel shows the three components: DGEBA (blue), dodecanedioic acid (green), and the octafunctional glycidyl POSS cage, cured with TBD at 2.5 mol% relative to carboxyl groups. The lower panel shows the resulting network, in which the T8 cage serves as an eight-arm junction and the orange markers indicate ester linkages formed on epoxide ring opening. The two insets show both states of the exchange: an ester bond with its neighbouring free hydroxyl, and the product after transesterification. That hydroxyl group is what carries the network dynamics. Redrawn from: Yang, H.; He, C.; Russell, T. P.; Wang, D. Giant 2020, 4, 100035. DOI: 10.1016/j.giant.2020.100035, Scheme 1.
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The mechanical results are unusual in that two properties normally traded against one another both improve. At 10 wt% POSS the ultimate tensile strength rises from 21.9 \u00b1 0.5 to 35.8 \u00b1 0.5 MPa, an increase of 63.5%, while the strain at break rises from 190 \u00b1 15% to 334 \u00b1 20%, an increase of 75.8%. Reinforcement almost always costs ductility, so simultaneous gains call for an explanation, and the authors attribute it to two distinct roles played by the cage. The eight glycidyl arms raise the crosslink density, which accounts for the strength, while the molecularly dispersed, nanoporous cage absorbs deformation energy, which accounts for the toughness.

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\"Tensile
Fig. 4. Strength and ductility increase together. Ultimate tensile strength and strain at break plotted against POSS loading. Both rise monotonically, which is atypical of filled systems, where reinforcement is normally paid for in ductility. Data from Yang, H.; He, C.; Russell, T. P.; Wang, D. Giant 2020, 4, 100035, Table 2. DOI: 10.1016/j.giant.2020.100035.
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Two properties move in the opposite direction. The Young's modulus falls from 799 \u00b1 11 to 632 \u00b1 23 MPa, and the glass transition temperature decreases from 34.8 to 27.1 \u00b0C by DMA and from 27.1 to 25.2 \u00b0C by DSC, with the 8 wt% sample departing from the trend in the DMA series and the 10 wt% sample departing from it in the DSC series. A decrease in Tg alongside an increase in crosslink density looks contradictory, and it is one of the more interesting details in the paper. The branched glycidyl POSS modifies the network topology and introduces a side-chain effect that outweighs the stiffening contributed by the additional junctions, an outcome previously documented for monofunctional POSS in epoxy networks by Abad and co-workers.

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POSS Vitrimer Relaxation Kinetics: Decoupling Creep Resistance from Processability

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The title of the Yang paper promises efficient relaxation, and the data say something more subtle. Stress relaxation at 160 \u00b0C slows from 7.4 minutes in the unfilled vitrimer to 27.0 minutes at 10 wt% POSS, a factor of 3.6. The activation energy for exchange rises from 82.26 \u00b1 2.05 to 107.90 \u00b1 3.48 kJ mol\u207b\u00b9, and the topology-freezing temperature climbs from 49.1 to 85.5 \u00b0C. Every one of these numbers points the same way: POSS slows the network dynamics.

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Read as a deficiency this would be a poor result, but that reading misses what the numbers describe. The network still relaxes completely at 1% strain, so it remains fully reprocessable, and the authors demonstrate this by cutting a specimen into pieces and remolding it with no loss of ultimate tensile strength across cycles. What changes is the temperature at which flow begins. A higher Tv means better creep resistance at service temperature, and a rubbery modulus at 150 \u00b0C that doubles from 1.77 to 3.75 MPa means better dimensional stability. The cage therefore separates two properties that are coupled in a conventional vitrimer: strength at the temperature of use and flow at the temperature of processing. That is precisely the function expected of a well-designed network junction.

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\"Relaxation
Fig. 5. Three independent measures of network dynamics agree. Relaxation time at 160 \u00b0C (7.4 to 27.0 min), activation energy for exchange (82.3 to 107.9 kJ mol\u207b\u00b9), and topology-freezing temperature (49.1 to 85.5 \u00b0C) all rise together on going from 0 to 10 wt% POSS. The network still relaxes completely; what changes is the rate, not the capacity. Data from Yang, H.; He, C.; Russell, T. P.; Wang, D. Giant 2020, 4, 100035, Table 2. DOI: 10.1016/j.giant.2020.100035.
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TBD-Catalyzed Siloxane Exchange in Vitrimers and the Role of the N\u2013H Proton

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While POSS has barely entered vitrimer chemistry, the silicon\u2013oxygen bond has entered it along two independent routes. The first was opened by Peng Zheng and Thomas McCarthy in 2012, who showed that siloxane equilibration provides a simple and robust self-healing mechanism in polysiloxanes. The limitation of that chemistry was speed: every material built on it relaxed over at least several hundred seconds, which places it outside any realistic industrial processing window.

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The breakthrough came from the Du Prez group at Ghent University. Tapas Debsharma and co-workers reported in JACS in 2022 a siloxane exchange pathway catalyzed by TBD in the presence of hydroxyl groups, mechanistically a proton shuttling process analogous to the TBD-catalyzed polymerization of cyclic siloxanes described by Fuchise, Shimada, and co-workers. They established the pathway with a model study in which 1,3-divinyltetramethyldisiloxane and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane were heated together at 120 \u00b0C for 16 hours under four sets of conditions. Silicon-29 NMR showed new resonances at 4.1 and 8.4 ppm, adjacent to the starting materials at 7.5 and 3.2 ppm, when both TBD and pentanol were present. Neither alcohol alone nor a metathesis-type pathway produced any exchange. TBD without added pentanol gave the same resonances only faintly, which the authors attribute to residual moisture or to silanol groups on the glass of the reaction vial, and which supports rather than weakens the role assigned to the hydroxyl.

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The mechanistic evidence rests not on a single control but on a screen of seven catalysts, and that is the most persuasive part of the work. The ionic bases all function, though not by a single route: tert-butoxide most likely deprotonates the secondary alcohol formed in the epoxy-amine reaction and starts the exchange as an alkoxide rather than as a siloxide, while trimethylsilanolate and tetramethylammonium siloxanolate supply siloxide directly. Loadings differ too, since tert-butoxide is inactive at 3 mol% and works at 6, and tetramethylammonium siloxanolate decomposes above 150 \u00b0C and has to be processed at 180 \u00b0C rather than 220 \u00b0C. Among the neutral organic bases only TBD works; MeTBD, DBU, and DMAP give no measurable exchange after an hour at 220 \u00b0C. The decisive comparison is the first pair. TBD and MeTBD have nearly identical basicity and differ only in that the N\u2013H group of MeTBD is capped with a methyl, yet capping that single proton switches the catalysis off completely. The failure of DBU and DMAP shows in addition that strong amidine or pyridine basicity is not on its own sufficient. Taken together, the screen indicates that the N\u2013H proton participates directly in the catalytic cycle rather than acting only through basicity.

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\"Catalytic
Fig. 6a. Proposed pathway for TBD-catalyzed siloxane exchange in the presence of hydroxyl groups. TBD acts as a proton shuttle, with the N\u2013H group participating directly in the cycle. The lack of catalytic activity shown by MeTBD, which has comparable basicity, supports this assignment. Redrawn from: Debsharma, T.; Amfilochiou, V.; Wr\u00f3blewska, A. A.; De Baere, I.; Van Paepegem, W.; Du Prez, F. E. J. Am. Chem. Soc. 2022, 144, 12280. DOI: 10.1021/jacs.2c03518, Scheme 2.
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\"Catalyst
Fig. 6b. The catalyst screen. The ionic bases tBuOK, SiMe\u2083OK, and TMAS all promote exchange by generating siloxide. Among the neutral organic bases only TBD is active; MeTBD, DBU, and DMAP give no measurable exchange. The comparison between TBD and MeTBD is decisive, since the two differ only by a methyl group on nitrogen and have essentially the same basicity. Redrawn from: Debsharma, T.; Amfilochiou, V.; Wr\u00f3blewska, A. A.; De Baere, I.; Van Paepegem, W.; Du Prez, F. E. J. Am. Chem. Soc. 2022, 144, 12280. DOI: 10.1021/jacs.2c03518, Scheme 3.
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The resulting material is prepared by curing DGEBA with the siloxane diamine at 120 \u00b0C in the presence of 10 mol% TBD relative to the Si\u2013O\u2013Si units. Its characteristic relaxation time is 5.6 s at 220 \u00b0C, the fastest siloxane exchange reported, with an activation energy of 87.2 \u00b1 0.9 kJ mol\u207b\u00b9 and a glass transition temperature near 85 \u00b0C. Thermogravimetry places 5% mass loss at 350 \u00b0C, and an isothermal hold at 220 \u00b0C for one hour costs about 1% of the mass. The network was mechanically reprocessed three times, recovering a relaxation time of roughly 6 s, a DSC Tg of 85 \u00b0C, and a soluble fraction near 1% on each occasion.

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The practical significance lies in the viscosity. The formulation measures 300 mPa\u00b7s at 25 \u00b0C, lower than commercial epoxy resins of comparable Tg, and it stays low for more than an hour of mixing. That allowed the authors to impregnate eight plies of plain-woven glass fabric at 220 g m\u207b\u00b2 by vacuum-assisted resin infusion, the technique used to manufacture wind turbine blades, and then to thermoform the cured laminate at 190 \u00b0C under 30 bar. A cured glass-fibre composite that can be reshaped after manufacture is a genuinely new object.

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Direct Silyl Ether Metathesis: Vitrimers Without Free Hydroxyl Groups

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The second route to dynamic Si\u2013O chemistry comes from Zhibin Guan's laboratory at UC Irvine, where Chase Tretbar, James Neal, and Guan reported the first example of direct silyl ether metathesis in JACS in 2019. The advance over earlier silyl ether systems is the removal of free hydroxyl groups from the network. Previous designs required a free alcohol as the exchange partner, and at elevated temperature alcohols open the door to dehydration, oxidation, and transesterification with acrylate backbones. Ether to ether metathesis avoids the problem entirely.

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The reaction was established on small molecules by mixing ethyltributoxysilane and ethyltripentoxysilane in anhydrous solvent and following the approach to the statistical 1:3:3:1 distribution of the four possible silanes by GC-MS. Without catalyst, full equilibration required 16.5 hours at 190 \u00b0C. Camphorsulfonic acid at 5 mol% proved the most effective of the catalysts tested, which also included zinc and scandium triflates. The polymer was then built from commodity material: poly(ethylene-co-vinyl acetate) with 6 mol% vinyl acetate was hydrolyzed quantitatively with sodium methoxide and the resulting alcohols were silylated with N,O-bis(trimethylsilyl)acetamide to give a trimethylsilyl ether functional polyethylene. Crosslinking used bis(methoxydimethyl)silyl octane, itself made in one step from the corresponding bis(chlorodimethyl)silyl octane and methanol, at 3 mol% of the available OTMS groups with 2 mol% camphorsulfonic acid, and gelation occurred in toluene at 80 \u00b0C.

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\"Silyl
Fig. 7. Two strategies for silyl ether dynamics. (A) Silyl ether\u2013hydroxyl exchange requires a free alcohol as the partner, and at elevated temperature that alcohol opens pathways to dehydration, oxidation, and transesterification. (B) Direct metathesis proceeds between two silyl ethers with no free alcohol involved, so the network loses its most reactive component while the Si\u2013OR motif remains thermally and oxidatively robust. This difference is what yields a vitrimer whose 5% mass loss occurs only at 427 \u00b0C. Redrawn from: Tretbar, C. A.; Neal, J. A.; Guan, Z. J. Am. Chem. Soc. 2019, 141, 16595. DOI: 10.1021/jacs.9b08876, Fig. 1.
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With a Si\u2013O bond dissociation energy near 535 kJ mol\u207b\u00b9 and no reactive hydroxyls present, the resulting vitrimer loses 5% of its mass only at 427 \u00b0C, which the authors identify as the highest value reported for a vitrimer at the time of publication in 2019. The activation energy for exchange is 77.8 kJ mol\u207b\u00b9, the topology-freezing temperature is 45 \u00b0C, and crosslinking raises the Young's modulus fivefold from 19.2 \u00b1 1 to 101 \u00b1 19 MPa. The cost of that stability appears in the kinetics: relaxation times run from 6456 s at 130 \u00b0C to 770 s at 170 \u00b0C.

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Comparing Si\u2013O Exchange Kinetics: Siloxane, Silyl Ether and Ester Vitrimers

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Placing the three systems on common axes, with the unfilled epoxy network as a baseline, makes the trade-off explicit. Each line below is an Arrhenius extrapolation anchored at a single published point using the reported activation energy, so the comparison rests on measured values rather than on digitized curves.

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\"Arrhenius
Fig. 8. The landscape of dynamic Si\u2013O exchange in vitrimers. TBD-catalyzed siloxane exchange (\u03c4* = 5.6 s at 220 \u00b0C) is more than two orders of magnitude faster than silyl ether metathesis (\u03c4* = 770 s at 170 \u00b0C), which in turn offers unmatched thermal stability (Td,5% = 427 \u00b0C). Transesterification in the epoxy\u2013POSS network is the slowest of the three up to roughly 175 \u00b0C, crossing below silyl ether metathesis only above that temperature. The fourth line is the unfilled epoxy vitrimer from the same study, shown as a baseline for what the cage changes. Markers are published values; lines are Arrhenius extrapolations from the reported activation energies. Compiled from three studies: Debsharma, T. et al. J. Am. Chem. Soc. 2022, 144, 12280. DOI: 10.1021/jacs.2c03518; Tretbar, C. A.; Neal, J. A.; Guan, Z. J. Am. Chem. Soc. 2019, 141, 16595. DOI: 10.1021/jacs.9b08876; Yang, H. et al. Giant 2020, 4, 100035. DOI: 10.1016/j.giant.2020.100035.
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Only the TBD-catalyzed siloxane system enters the window below 60 s where industrial compression molding becomes practical. Silyl ether metathesis buys thermal stability at the price of roughly three orders of magnitude in rate, and the epoxy\u2013POSS transesterification network, with the highest activation energy of the three at 107.9 kJ mol\u207b\u00b9, is the most temperature-sensitive and therefore the one whose processing window is most sharply defined.

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Octaglycidyl POSS in a Disulfide-Exchange Silicone Vitrimer

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One study has already brought the two worlds together, although it was not framed that way. Cheng'e Yue and co-workers at Harbin University of Science and Technology published a vitrimeric silicone composite for thermal interface applications in the Journal of Colloid and Interface Science in 2022. The matrix is a siloxane epoxide, prepared by Karstedt-catalyzed hydrosilylation of allyl glycidyl ether with 1,1,3,3-tetramethyldisiloxane, cured with 4-aminophenyl disulfide so that aromatic disulfide metathesis supplies the dynamic chemistry. The filler is boron nitride nanosheets, exfoliated by sonication, hydroxylated, and surface-modified with (3-glycidoxypropyl)trimethoxysilane to improve compatibility with the matrix. The third component is octaglycidyl POSS, the same cage and the same supplier as in the Yang study, blended at a DGESi:APDS:POSS weight ratio of 100:60:x and cured at 150 \u00b0C for two hours in air.

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\"Synthesis
Fig. 9. Construction of the vitrimeric silicone composite. Hydrosilylation of 1,1,3,3-tetramethyldisiloxane with allyl glycidyl ether over Karstedt's catalyst gives the difunctional siloxane epoxide DGESi, which is then cured with 4-aminophenyl disulfide in the presence of octaglycidyl POSS. In the resulting network the POSS cage acts as a junction while the aromatic disulfide bridges carry the dynamics, and it is their exchange that provides self-healing and reprocessability. Redrawn from: Yue, C.; Zhao, L.; Guan, L.; Zhang, X.; Qu, C.; Wang, D.; Weng, L. J. Colloid Interface Sci. 2022, 620, 273. DOI: 10.1016/j.jcis.2022.04.017, Fig. 1a.
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At 10 wt% POSS the tensile strength increases 2.82-fold to 8.4 \u00b1 0.1 MPa. The thermally conductive composites were built on the POSS-5 matrix rather than POSS-10, and with 66 wt% functionalized boron nitride their thermal conductivity reaches 1.41 \u00b1 0.05 W m\u207b\u00b9 K\u207b\u00b9, more than six times that of the unfilled elastomer, and the healing efficiency remains at 92.0 \u00b1 1.5% against 98.8 \u00b1 1.1% for the unfilled matrix. Thermal conductivity recovers to 99.3% of its original value after six healing cycles.

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The detail most easily missed concerns the glass transition. In this work POSS raises Tg from 45.4 \u00b1 0.2 to 51.1 \u00b1 0.4 \u00b0C, whereas in the Yang study it lowered Tg. The same cage, from the same supplier, produces opposite effects in two different matrices, because the network topology and the mode of incorporation differ. That single observation is a compact statement of how much remains unexamined.

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Can the T8 Cage Backbone Itself Be the Exchange Site?

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The established facts can be summarized briefly. The silicon\u2013oxygen bond is thermodynamically strong at roughly 535 kJ mol\u207b\u00b9 and kinetically labile under the right conditions, a combination that makes it an excellent dynamic motif. It can be exchanged quickly, in 5.6 s with TBD and a hydroxyl partner, or exchanged with exceptional stability, surviving to 427 \u00b0C through silyl ether metathesis. The T8 cage incorporated as a filler into a vitrimer network raises strength and ductility simultaneously, increases Tv, and decouples creep resistance from processability.

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What has not been examined is what happens when the cage stops being a filler and becomes the carrier of the dynamic chemistry. In all three network studies the cage is an additive. It sits in the network, it raises the crosslink density, and it modifies the mechanical response, but the exchange happens somewhere else: on the ester bonds of the matrix, on the disulfide bridges, on the siloxane units of the hardener. The cage is a passive junction in a dynamic network.

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It is worth separating three levels at which a cage can participate. At the first level the cage is a nanoscale filler and the exchange happens entirely in the surrounding matrix, which is what every study described above actually demonstrates. At the second level the cage becomes a multifunctional covalent junction whose vertices carry the dynamic groups, and this has been explored in part, since the glycidyl arms in the Yang network do sit adjacent to the exchanging esters. The third level has not been reached at all, and it is the one where the Si\u2013O\u2013Si bridges of the cage framework themselves take part in associative exchange.

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That third level is not an exotic proposal. The T8 cage is built from twelve Si\u2013O\u2013Si bridges, structurally the same linkage that Du Prez and co-workers exchange in 5.6 s. The question it raises, and one that appears not to have been put, is whether a silsesquioxane cage in the presence of TBD and hydroxyl groups becomes a dynamic junction in its own right, so that the cage framework rather than its substituents carries the topology rearrangement.

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A positive result is not guaranteed, and the structural arguments cut both ways. The Si\u2013O\u2013Si angles in the cubic cage are strained relative to linear siloxanes, which could make the bridges more susceptible to nucleophilic attack and therefore faster to exchange. The same strain, however, means that an opened cage has no straightforward route back to the closed structure, so exchange could lead to irreversible cage opening and condensation into ladder or resinous architectures rather than to clean associative exchange. The cage might also simply be unreactive on the timescale of the experiment, since the bridging oxygens are sterically shielded by eight substituents pointing outward from the vertices.

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A Silicon-29 NMR Control Experiment to Test POSS Cage Exchange

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The first question to settle is narrow and cheap to answer. Octaglycidyl POSS, or any soluble T8 cage, is held at 220 \u00b0C in the presence of 10 mol% TBD and a hydroxyl source under the conditions that produce fast siloxane exchange in the Du Prez system, and the cage is monitored by silicon-29 NMR. Every silicon in a closed T8 cage carries three siloxane bridges, so the cage is a T\u00b3 species and gives a single symmetric resonance; the Wroc\u0142aw group reports \u221266.2 ppm for their octa-functionalized cages, and values between roughly \u221266 and \u221270 ppm are typical for alkyl-substituted cages. Survival of the cage would show that one resonance persisting throughout. Opening a bridge converts two silicons from T\u00b3 to T\u00b2, and those T\u00b2 signals appear well downfield of the cage, in the region around \u221256 to \u221260 ppm. Cage opening would therefore announce itself as new T\u00b2 intensity, loss of the symmetry that makes all eight silicon atoms equivalent, and in the limit a broad envelope characteristic of a condensed resin.

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Either outcome is informative. If the cage survives, the next experiment is a crossover study with two differently substituted cages, following the design Debsharma and co-workers used for their disiloxane model compounds, to establish whether exchange occurs at the cage framework at all. If the cage opens, the result sets a clear boundary on how aggressive the catalysis can be in any POSS vitrimer and explains why cage-based dynamic networks have not appeared. The reagents are commercial, the instrumentation is standard, and the experiment occupies an afternoon.

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Outlook: Where POSS and Vitrimer Chemistry Meet Next

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Taken together, these five studies describe a field in which two mature chemistries have remained almost entirely separate. Vitrimer design has converged on the silicon\u2013oxygen bond as one of its most capable dynamic motifs, and silsesquioxane chemistry provides the most precisely defined Si\u2013O architecture available, a monodisperse cage with eight equivalent vertices and twelve equivalent bridges. The only published point of contact treats the cage as a filler, and even in that role it decouples properties that are otherwise coupled. Whether the cage can also serve as the exchange site is an open structural question with a cheap first experiment and a publishable answer in either direction.

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A second pattern runs through these studies. Dynamic Si\u2013O chemistry connects applications that appear unrelated, from the reshaping of glass-fibre composites destined for wind turbine blades to the thermal management of integrated circuits, and in each of them the silsesquioxane cage appears as the least examined variable. That is usually a sign of where the next result is to be found.

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Frequently Asked Questions About POSS Vitrimers

What is a POSS vitrimer?

A POSS vitrimer is a covalent adaptable network in which polyhedral oligomeric silsesquioxane cages are built into a vitrimer matrix. The network rearranges its topology by associative exchange, so the crosslink density never drops, while the T8 cage acts as a rigid, molecularly dispersed, eight-arm junction. In every published example the exchange chemistry itself sits in the matrix rather than on the cage.

Does POSS make a vitrimer stronger or more brittle?

Both strength and ductility improve, which is unusual for a filled network. At 10 wt% loading the tensile strength rises 63.5% and the strain at break 75.8%. The eight glycidyl arms raise the crosslink density while the nanoporous cage absorbs deformation energy. The Young's modulus and the glass transition temperature fall slightly.

How fast is siloxane exchange compared with other vitrimer chemistries?

TBD-catalyzed Si\u2013O\u2013Si exchange relaxes in 5.6 s at 220 \u00b0C, which puts it inside the window for industrial compression molding. Direct silyl ether metathesis is roughly three orders of magnitude slower (770 s at 170 \u00b0C) but survives to 427 \u00b0C. Hydroxyl\u2013ester transesterification in the epoxy\u2013POSS network is the slowest of the three below about 175 \u00b0C.

Can the Si\u2013O\u2013Si bridges of the T8 cage act as dynamic bonds?

Nobody has tested it. The cage contains twelve Si\u2013O\u2013Si bridges, structurally the same linkage that exchanges in 5.6 s under TBD catalysis, but the strained cage geometry could equally lead to irreversible ring opening. A silicon-29 NMR experiment on a soluble T8 cage held with TBD and a hydroxyl source would settle the question in an afternoon.

References

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  1. Yang, H.; He, C.; Russell, T. P.; Wang, D. Epoxy-polyhedral oligomeric silsesquioxanes (POSS) nanocomposite vitrimers with high strength, toughness, and efficient relaxation. Giant 2020, 4, 100035. DOI: 10.1016/j.giant.2020.100035
  2. Debsharma, T.; Amfilochiou, V.; Wr\u00f3blewska, A. A.; De Baere, I.; Van Paepegem, W.; Du Prez, F. E. Fast Dynamic Siloxane Exchange Mechanism for Reshapable Vitrimer Composites. J. Am. Chem. Soc. 2022, 144, 12280\u201312289. DOI: 10.1021/jacs.2c03518
  3. Tretbar, C. A.; Neal, J. A.; Guan, Z. Direct Silyl Ether Metathesis for Vitrimers with Exceptional Thermal Stability. J. Am. Chem. Soc. 2019, 141, 16595\u201316599. DOI: 10.1021/jacs.9b08876
  4. Yue, C.; Zhao, L.; Guan, L.; Zhang, X.; Qu, C.; Wang, D.; Weng, L. Vitrimeric silicone composite with high thermal conductivity and high repairing efficiency as thermal interface materials. J. Colloid Interface Sci. 2022, 620, 273\u2013283. DOI: 10.1016/j.jcis.2022.04.017
  5. Denissen, W.; Winne, J. M.; Du Prez, F. E. Vitrimers: permanent organic networks with glass-like fluidity. Chem. Sci. 2016, 7, 30\u201338. DOI: 10.1039/C5SC02223A
  6. Montarnal, D.; Capelot, M.; Tournilhac, F.; Leibler, L. Silica-Like Malleable Materials from Permanent Organic Networks. Science 2011, 334, 965\u2013968. DOI: 10.1126/science.1212648
  7. Mauro, J. C.; Yue, Y.; Ellison, A. J.; Gupta, P. K.; Allan, D. C. Viscosity of glass-forming liquids. Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 19780\u201319784. DOI: 10.1073/pnas.0911705106
  8. Zheng, P.; McCarthy, T. J. A Surprise from 1954: Siloxane Equilibration Is a Simple, Robust, and Obvious Polymer Self-Healing Mechanism. J. Am. Chem. Soc. 2012, 134, 2024\u20132027. DOI: 10.1021/ja2113257
  9. Hajiali, F.; Tajbakhsh, S.; Mari\u0107, M. Thermally reprocessable bio-based polymethacrylate vitrimers and nanocomposites. Polymer 2021, 212, 123126. DOI: 10.1016/j.polymer.2020.123126
  10. Cieplucha, M.; Janeta, M.; Szafert, S. Hybrid inorganic\u2013organic polyhedral oligomeric silsesquioxane-based poly(1-haloacetylene)s: thermal, solid-state polymerization. Materials Chemistry Frontiers 2025, 9, 3034. DOI: 10.1039/d5qm00583c
  11. Abad, M. J.; Barral, L.; Fasce, D. P.; Williams, R. J. J. Epoxy networks containing large mass fractions of a monofunctional polyhedral oligomeric silsesquioxane (POSS). Macromolecules 2003, 36, 3128\u20133135. DOI: 10.1021/ma021539f
  12. Fuchise, K.; Igarashi, M.; Sato, K.; Shimada, S. Organocatalytic controlled/living ring-opening polymerization of cyclotrisiloxanes initiated by water with strong organic base catalysts. Chem. Sci. 2018, 9, 2879\u20132891. DOI: 10.1039/c7sc04234e
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Fast Dynamic Siloxane Exchange Mechanism for Reshapable Vitrimer Composites. Journal of the American Chemical Society, 144(27), 12280\u201312289."},{"id":"https://doi.org/10.1021/jacs.9b08876","unstructured":"Tretbar, C. A., Neal, J. A., & Guan, Z. (2019). Direct Silyl Ether Metathesis for Vitrimers with Exceptional Thermal Stability. Journal of the American Chemical Society, 141(42), 16595\u201316599."},{"id":"https://doi.org/10.1016/j.jcis.2022.04.017","unstructured":"Yue, C., Zhao, L., Guan, L., Zhang, X., Qu, C., Wang, D., & Weng, L. (2022). Vitrimeric silicone composite with high thermal conductivity and high repairing efficiency as thermal interface materials. Journal of Colloid and Interface Science, 620, 273\u2013283."},{"id":"https://doi.org/10.1039/c5sc02223a","unstructured":"Denissen, W., Winne, J. M., & Du Prez, F. E. (2016). Vitrimers: permanent organic networks with glass-like fluidity. Chemical Science, 7(1), 30\u201338."},{"id":"https://doi.org/10.1126/science.1212648","unstructured":"Montarnal, D., Capelot, M., Tournilhac, F., & Leibler, L. (2011). Silica-Like Malleable Materials from Permanent Organic Networks. Science, 334(6058), 965\u2013968."},{"id":"https://doi.org/10.1073/pnas.0911705106","unstructured":"Mauro, J. C., Yue, Y., Ellison, A. J., Gupta, P. K., & Allan, D. C. (2009). Viscosity of glass-forming liquids. Proceedings of the National Academy of Sciences, 106(47), 19780\u201319784."},{"id":"https://doi.org/10.1021/ja2113257","unstructured":"Zheng, P., & McCarthy, T. J. (2012). A Surprise from 1954: Siloxane Equilibration Is a Simple, Robust, and Obvious Polymer Self-Healing Mechanism. Journal of the American Chemical Society, 134(4), 2024\u20132027."},{"id":"https://doi.org/10.1016/j.polymer.2020.123126","unstructured":"Hajiali, F., Tajbakhsh, S., & Mari\u0107, M. (2021). Thermally reprocessable bio-based polymethacrylate vitrimers and nanocomposites. Polymer, 212, 123126."},{"id":"https://doi.org/10.1039/d5qm00583c","unstructured":"Cieplucha, M., Janeta, M., & Szafert, S. (2025). Hybrid inorganic\u2013organic polyhedral oligomeric silsesquioxane-based poly(1-haloacetylene)s: thermal, solid-state polymerization. Materials Chemistry Frontiers, 9(20), 3034\u20133043."},{"id":"https://doi.org/10.1021/ma021539f","unstructured":"Abad, M. J., Barral, L., Fasce, D. P., & Williams, R. J. J. (2003). Epoxy Networks Containing Large Mass Fractions of a Monofunctional Polyhedral Oligomeric Silsesquioxane (POSS). Macromolecules, 36(9), 3128\u20133135."},{"id":"https://doi.org/10.1039/c7sc04234e","unstructured":"Fuchise, K., Igarashi, M., Sato, K., & Shimada, S. (2018). Organocatalytic controlled/living ring-opening polymerization of cyclotrisiloxanes initiated by water with strong organic base catalysts. Chemical Science, 9(11), 2879\u20132891."}],"rid":"yba07-a3p15","summary":"Epoxy nanocomposite vitrimers containing polyhedral oligomeric silsesquioxane (POSS) were reported by Hongkun Yang, Changfei He, Thomas P. Russell, and Dong Wang in Giant in 2020. Studies devoted specifically to POSS in vitrimer networks remain scarce, and this one still carries the subject almost on its own.","tags":["Covalent Adaptable Network","Dynamic Covalent Chemistry","POSS","Siloxane Exchange","Silsesquioxane"],"title":"POSS Vitrimers: The Cage as a Dynamic Si\u2013O\u2013Si Node","updated_at":1791045319,"url":"https://silsesquioxane.blogspot.com/2026/10/poss-vitrimers-dynamic-siloxane-cage.html","version":"v1"}},{"document":{"authors":[{"contributor_roles":[],"family":"Fix","given":"Blair"}],"blog":{"authors":null,"community_id":"0b9cb48f-680d-4f11-99f0-5b61a55fe4cc","created":1714262400,"current_feed_url":null,"description":"New ideas in economics and the social sciences","doi":"https://doi.org/10.59350/etd","favicon":"https://rogue-scholar.org/api/communities/0b9cb48f-680d-4f11-99f0-5b61a55fe4cc/logo","feed_format":"application/atom+xml","feed_url":"https://economicsfromthetopdown.com/feed/atom/","filter":null,"generator":"Other","home_page_url":"https://economicsfromthetopdown.com/","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"etd","status":"active","subfield":"2002","title":"Economics from the Top Down","updated":1791029100,"use_api":true},"blog_name":"Economics from the Top Down","blog_slug":"etd","content_html":"\"\"
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Given our current landscape of AI hype and doom, everyone seems to have an opinion about whether chatbots are 'good' or 'bad'. Fewer people have thought about how chatbots fit into the long-term history of automation. And even fewer folks have reflected on the conceptual requirements that make automation useful. Here are my thoughts on this latter topic.

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In my view, automation is useful when it meets two criteria:

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  1. The product is more important than the process that creates it.\n
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  2. The product can be validated without auditing the creation process.\n
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If we look at successful forms of machine automation, they tend to meet both criteria. For example, think of a pencil factory that automates the production of pencils. Here, the pencil is the 'product', and whatever happens inside the factory is the 'process'.

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Now for the end user, the process of pencil production is largely irrelevant. It doesn't matter if the pencil is hand crafted, built in an assembly line, or conjured by a Star Trek replicator. As long as the pencil works in the hands of the user, its creation process is unimportant.

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That brings me to the second requirement for useful automation: the product must be easily validated. To validate that a pencil works, you don't need to audit the process that created it. You just give the thing a go. Yup, this pencil works. Nope, that one's a dud.

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Thinking more broadly, the history of automation has been dominated by this sort of process where a machine replaces human labor in the production of some sort of physical commodity. The automation works because (1) the commodity is valued more than the process that creates it, and (2) it's easy to verify the quality of the commodity without auditing the entire chain of production.

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Intellectual automation

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Looking to more recent technological progress, it turns out that successful automation need not be physical. Intellectual automation can also be useful. Just look at computers, which owe their name to the desire to automate computation.

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Many forms of computation pass our automation requirements: the product is more important than the process, and the process is easy to validate. For example, when I ask a computer to calculate \\sqrt{200} , I don't care about the algorithm it uses, or about the details of its chipset. I just want the answer. Likewise, once I have the result, I don't have to audit the computer's innards to validate the answer. I just check that the number squares to give 200.

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In more general terms, any intellectual task that meets our two requirements is game for computer automation. But for years, some forms of intellectual work seemed beyond the reach of computers. Writing code is a good example. Historically, programming was a tedious task that took years of specialized training. But with the rise of neural nets and their associated chatbot interfaces, these barriers are being torn down. Chatbots can now code more quickly than any human. But is this ability useful?

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Well, the answer depends on whether the application passes our two requirements. (Is the product more important than the process? And can the product be verified without auditing the process that created it?) Clearly, many forms of coding pass this test. Web design is an obvious example. When a blogger asks for a nice website, they usually don't care how it's accomplished. Likewise, the blogger can easily tell if the final design is what they want. (They just browse the website.)

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In short, chatbots are useful for automating intellectual tasks like web design (and any other easily verified piece of software). Yes, the bots will put some folks out of work. Yes, they'll raise questions about the skills required in the workforce. And yes, they'll be used in ways that undermine labor power and harm workers' health. But these issues are nothing new. They're a historical feature of all forms of automation. What interests me more (at least in this essay) is the ways in which chatbot automation might be fundamentally useless, or even downright harmful.

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On the useless front, I'm skeptical that chatbots can be used to fully automate scientific analysis. Here's why. When a scientist analyzes their data, they might think that the product of their inquiry is the 'results' section in their published paper. And in some sense, that's true. But the (big) caveat is that the usefulness of this result depends on whether the analysis pipeline is correct.

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Now, suppose that a scientist automated their work by getting a chatbot to code the entirety of their analytic pipeline. How does the scientist know that their results are correct?1 Well, if the analysis is complicated, the only sound way to assess its correctness is to audit the underlying code. That requires significant time and skill. Meanwhile, this time-skill investment largely defeats the purpose of automation. Of course, chatbots can no doubt help scientist solve specific coding problems. (These bots lower the barrier to successful programming.) But the notion that chatbots will fully automate scientific analysis is, frankly, laughable.

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True, some academics will surely try this fully automated approach. In fact, I expect that the scientific literature will become increasingly polluted with bot junk. But I'd argue that we can't blame chatbots (solely) for this pollution. The root problem is the incentive structure in universities \u2014 a structure that values the production of academic papers far more than the process that creates them. But when it comes to good research, its social value lies entirely in the scientific process.

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Process dependence

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Like science, many areas of human life have a process dependence, in which the usefulness of a 'product' hinges solely on the process of doing it. Schooling is the most ubiquitous example. When a teacher asks students to solve a math problem, the product of this task is the correct answer. But the usefulness of this activity lies mostly in the process of doing it. Sure, a calculator will tell you the sum of 21 + 54. But if the goal is to learn basic arithmetic, the use of a calculator is not 'automation'. It's cheating.

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The obvious conclusion is that skill acquisition cannot be automated. If the goal is to learn basic arithmetic, a calculator is self-defeating. If the goal is learn to the principles of English spelling, a spell checker is unhelpful. If the goal is to learn to read, a text-to-voice processor is educational sabotage. And if the goal is to learn to write, well, chatbots are your mortal enemy.2

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In this light, we can think of formal education as a teaching method that forces students to re-experience, in a curated and abbreviated form, problems that long stumped our ancestors. For example, it took thousands of years of doing arithmetic before humans automated the job with calculators. By then, mathematics was a mature field. When today's students learn math, they replay this history over the course of a few years. At first, 'math' consists solely of raw computation. Later on, students learn more symbolic logic, and the number crunching gets delegated to machines. In short, when it comes to intellectual automation, everything hinges on the order of operations. First, you learn a difficult skill; then you discover that you can automate it.

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Do not automate

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Thinking further about process dependence, it seems likely that some intellectual tasks should never be automated. Writing is the most obvious example.

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To understand why automated writing is bad, we need to first deal with the overloaded nature of the English language. In English, the word 'write' has a misleading double meaning. In one sense, to 'write' means to 'scribe' \u2014 to put an already existing sentence onto paper. This form of 'writing' takes skill, but is grounds for useful automation. Once upon a time, video captions were transcribed by a human listener. But today, the captioning can be generated by natural language processors.

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The problem with automated 'writing' comes with the second meaning of the word. To 'write' is not just to scribe; it's also to craft a set of coherent arguments that other humans can follow and understand. To automate this activity is an oxymoron, because the product (a rational argument) can't be separated from the process itself. Or as my mentor Jonathan Nitzan once told me, \"You don't really know what you think until you write it down.\"

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Here's what he means. 'Writing', in this sense of the word, is essentially codified thinking. When an idea is written down, reading this idea leads to all kinds of interesting consequences. Often, the writer realizes that the idea is vague or incomplete. And so they revise it until things make sense. Once the idea is coherent, rereading it prompts new ideas and new connections. Many are dead ends. Some are fruitful.

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To be frank, this iterative process can be torturous. When I write blog posts about my research, the final essay usually conceals an iceberg of revised or discarded thought. Sure, I'd like to avoid this torture and still have the final well-argued essay. But to avoid the torture of 'writing' is to avoid the discomfort of rational thought. Automating this task does not 'save time'; it saves us from thinking.

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Automation for whom?

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For automation to be 'useful', the product must be more important than the process by which it is created. But there is a sticky question that I've so far avoided: more important for whom?

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For the user of a pencil, the way that this commodity was manufactured is largely irrelevant. But for the folks who live beside the pencil factory, the manufacturing process is often more salient than the product itself, particularly if pollution is involved. Likewise, chatbots might be great for the Silicon Valley programmer, but they're a Faustian bargain for the utility planners who have to power local data centers.

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When it comes to the big picture of automation, the process by which it occurs is incredibly consequential \u2026 often far more so than the product being automated. It's one thing to have a Star-Trek-like computer powered by nuclear fusion; it's quite another to have a sycophantic chatbot powered by fossil fuels.

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Unfortunately, we humans are notoriously bad at assessing the big-picture consequences of our automation schemes. As a rule, we build first and ask questions later. Today, we seem to be automating tasks that should not be automated (using fuels that are steadily spoiling the planet). The internet is increasingly littered with chatbot slop, to the point that search engines can feel pointless. If a search query returns page after page of bot slop, it's obviously more sensible to pose the question directly to a chatbot. But if the chatbot is trained on bot-slop, how can you trust its answer?

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Now, I'm personally skeptical of claims about AI-driven doom, but mostly because they go in the wrong direction. If there's a risk that AI will kill industrial civilization, it's not because the machines will take over. Far more likely, in my opinion, is that we get a future that looks like an anti-singularity \u2014 a future in which our technology becomes so powerful (and so polluting) that it gradually undermines its own existence. As humans subcontract thinking to fossil-fuel-fed chatbots, the information environment (as well as the natural environment) becomes polluted with slop, and the slop-trained bots themselves grow increasingly senile. \"Water the crops with Brawndo,\" the bots say. Meanwhile, AI-driven education has left humans gullible enough to listen.3

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In short, automation can be useful if it frees us from drudgery (in a way that doesn't destroy the earth) and leaves more time for creative thought. But if automated chatbots gobble fossil fuels in order to liberate us from thinking, well, civilization had a nice run.

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Support this blog

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Hi folks, Blair Fix here. I'm a crowdfunded scientist who shares all of my (painstaking) research for free. If you think my work has value, consider becoming a supporter. You'll help me continue to share data-driven science with a world that needs less opinion and more facts.

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This work is licensed under a Creative Commons Attribution 4.0 License. You can use/share it anyway you want, provided you attribute it to me (Blair Fix) and link to Economics from the Top Down.

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Notes

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  1. Of course, the truth is that even the best-trained scientists make mistakes, which is why good science requires replication. And regarding code, there's an old saying that you shouldn't reinvent the wheel \u2026 don't recode an algorithm that someone has already solved. Which is why scientific code is typically full of libraries and functions which the scientist in question did not write.\n

    For example, when I get R to calculate a matrix inverse, I'm actually calling ancient Fortran code for doing linear algebra. To me, this code is a black box \u2014 I have no idea how it works. So how do I know that this code works correctly? Honestly, it's a matter of trust. These libraries are free and open source, and have been used for ages. If they had a gaping problem, scientists would not use them.

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    Now, this game of trust comes on a continuum. I greatly trust R's matrix inverse functions. I put less trust in code from a random Github repository. And I put even less trust in the code delivered by a chatbot. Sure, the chatbot code may be 99% good. But that 1% bad stuff can be a killer. Imagine a world in which all scientific analysis and all scientific libraries were coded by chatbots with no supervision from scientists. Each time a bot calls a Python or R library, there's a 1% chance of error. As the code expands, the error compounds, to the point that virtually everything the bots spit out is wrong.

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    Still, chatbots shine in the domain where automation has always been useful \u2014 when the results are easily verifiable. Refactoring code is a good example. If I do an analysis in R and someone else wants to refactor the code into Python, a chatbot could make short work of the task. Sure, the chatbot might make mistakes along the way, but the user could tell by comparing the R output to the Python output.\"\u21a9\"\ufe0e\n

    2. \n
  2. In schools systems, teachers often speak in the language of 'accommodations' \u2014 as in text-to-voice is an 'accommodation' for dyslexia. While this use of technology is well intentioned, it's also tragic. The truth is that if a teenager cannot read effectively, all available resources should go into solving this highly solvable problem. In my view, it's unethical to forge ahead with other curriculum in the face of gaping illiteracy.\"\u21a9\"\ufe0e\n
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  3. If there are long-term benefits to chatbots, they will come by strategically withholding chatbot use while students learn difficult and uncomfortable skills. Actually using a chatbot takes about as much skill as using a calculator. Which is funny, because no one would propose a 'calculator-driven education'. But many folks will claim that AI is going to revolutionize schooling. Well, I work in high schools and can tell you that so far, what's been 'revolutionary' is that chatbots have killed the take-home essay. Learning to craft long-form thought used to be a standard feature of high-school education. Now it's not.\"\u21a9\"\ufe0e\n
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Further reading

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\nDoctorow, C. (2026). The reverse centaur's guide to life after AI: How to think about artificial intelligence before it's too late. Verso Books.\n

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The post The Laws of Useful Automation appeared first on Economics from the Top Down.

","doi":"https://doi.org/10.59350/rgz3a-njq17","guid":"https://economicsfromthetopdown.com/?p=15696","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790985600,"rid":"m3k2b-jkd40","summary":"Your browser does not support the audio tag. Download: PDF | EPUB | MP3 | WATCH VIDEO Given our current landscape of AI hype and doom, everyone seems to have an opinion about whether chatbots are 'good' or 'bad'. Fewer people have thought about how chatbots fit into the long-term history of automation. And even fewer folks have reflected on the conceptual requirements that make automation useful. Here are my thoughts on this latter topic.","tags":["Academic Work","AI Doom","AI Hype","Anti-singularity","Automation"],"title":"The Laws of Useful Automation","updated_at":1791029107,"url":"https://economicsfromthetopdown.com/2026/10/03/the-laws-of-useful-automation/","version":"v1"}},{"document":{"authors":[{"contributor_roles":[],"family":"Baroncini","given":"Sofia"}],"blog":{"authors":null,"community_id":"be4c775e-c004-4189-8322-25abe1cc96c9","created":1737676800,"current_feed_url":null,"description":"Leibniz Institute of European History (IEG)","doi":null,"favicon":"https://rogue-scholar.org/api/communities/be4c775e-c004-4189-8322-25abe1cc96c9/logo","feed_format":"application/atom+xml","feed_url":"https://dhlab.hypotheses.org/feed/atom/","filter":null,"generator":"WordPress","home_page_url":"https://dhlab.hypotheses.org","issn":null,"language":"deu","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":null,"relative_url":null,"secure":true,"slug":"dhlab","status":"active","subfield":"1202","title":"DH Lab","updated":1790323745,"use_api":true},"blog_name":"DH Lab","blog_slug":"dhlab","content_html":"

Introduction: What is an ontology?

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Everything we can do on a computer is encoded; namely, a sequence of 0-1 bits is associated with symbolic content. This is the core fundamental principle allowing us to do a range of different operations on a computer, from writing a document in Word to viewing an image.

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If everything can be encoded through this kind of association, then machines can compute meanings as well. Since the 1950s, the branch of symbolic AI has researched the possibility of doing a detailed description of the world, in the form of concepts and relations, and associating them with logical rules. In this way, a computer could do sophisticated operations, such as inferring knowledge not directly stated in the data. For example, if the data states that Sonia is the sister of Juliette and Alice, and the relation is declared as being transitive, then the system could infer that Juliette and Alice are sisters, too.

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One application of this approach is ontologies, in other words, a structured way, processable by computers, of describing a particular domain of knowledge. It identifies the main concepts in that domain and, most importantly, the relationships between them. For example, in a project about works of art, an ontology might define concepts such as Person, Artwork, the Creation Event, Institutions holding the artwork, the Iconography depicted, and so on. In this sense, an ontology does more than provide a list of terms. It provides a shared conceptual framework that helps both humans and computers understand how different pieces of information are connected.

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Furthermore, an ontology can also state logical rules allowing the system to infer further information, or to check that data is described correctly. For example, in Figure 1, the ontology states that the concept \"Artist\" is a subclass of \"Person\". If, in the dataset, \"Monet\" is described as \"Artist\", the computer, through a reasoner (i.e., a software tool that automatically checks the logical consistency of the ontology and derives new facts from it), can infer that Monet is not only an artist, but also a person. This means that in a dataset in which all people are described according to their profession, and all the professions are stated as a subclass of \"Person\", we can easily retrieve all the people in the dataset although none of them is explicitly described as a person.

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\"Figure
Figure 1. Example of how an ontology can be used to infer further knowledge. If in the graph dataset I insert the information that Monet is an Artist, and the ontology \"Artist\" is stated as being subclass of \"Person\", then the computer can infer that Monet is also a \"Person\", without the need to manually enter that information. Figure by Sofia Baroncini
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A key concept is the distinction between the ontology itself, defining classes or concepts, and data described according to that ontology, representing individuals or instances (see Figure 2). Whereas the first describes how the types of entities relate to each other and represents the domain in abstract terms (e.g., \"Artist\" is a subclass of \"Person\"), the latter contains the actual content (\"Monet\"). In other words, it is similar to the difference between an Excel sheet showing only the column names and the same sheet filled with actual data: the columns give us information about how the data is organized (\"People\"), whereas the rows are the actual individuals (\"Monet\", \"Picasso\", etc.). In ontology development, these are also called \"T-BOX\" and \"A-BOX\". The actual content needs to follow the structure defined in the ontology, as shown in Figure 2.

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From a technical point of view, ontologies are commonly formalized in a specific language, OWL 2 (Web Ontology Language 2), which defines the logical relations among entities, and in the RDF Schema, a light and less expressive vocabulary to define classes, subclasses, and relations. Ontologies can be easily created with Prot\u00e9g\u00e9, an open-source program with a user-friendly interface to create entities and relations and options for saving them in OWL.

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\"Figure
Figure 2. Demonstrative example of an ontology (in orange) describing the classes or entities and their properties or relations in a domain of knowledge, also called \"T-Box\", and the individuals or instances represented according to the ontology (in yellow), also called \"A-Box\". As the ontology states that Paintings can depict (relation \"depicts\") an Iconography, we can reuse this pattern to express that the individual painting \"La Primavera\" by Botticelli depicts the three graces, another individual having as type the entity Iconography. Relations must be stated in the ontology to be used in data, and must respect the direction of the arrow. For example, when applying this ontology, we can't say that an iconography depicts an artwork \u2013 it should always be the contrary. Figure by Sofia Baroncini
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Several languages and applications exist. One of the most common areas of application in the DH sector is in the Semantic Web. Semantic Web is an extension of the hypertext web in which not only web pages, but also concepts are related to each other. URIs are used not only to identify web pages, but also to identify concepts, entities, and relationships. For example, this URI on Wikidata identifies the Mona Lisa painting, and it also states, through the URI indicating the relationship of \"creator\", that it was painted by Leonardo da Vinci, associated with another URI.

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The benefits of the Semantic Web and ontologies in general are multiple. They help algorithms to clearly identify concepts and differentiate among them, even if they have the same name (e.g., \"Venus\" as a planet is different from \"Venus\" indicating the deity of love in Greek mythology). As computers can process this information, computational operations are done with semantic data. An example is protein prediction in the field of biology, done through ontologies and Machine Learning.

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In the humanities area, ontologies are mainly used as standards to guarantee interoperability between datasets maintained by different institutions in the GLAM (Galleries, Libraries, Archives, Museums) sector. If structured data is described according to the same ontology, data can be integrated and queried together, even though separate datasets are created and maintained by different institutions. In this way, a global, interconnected knowledge graph can be created in a decentralized way. The use of ontologies to describe data is an important component of the creation of Linked (Open) Data, i.e., a network of integrated data described using common, open ontologies. The linked data cloud describes the massive, growing amount of LOD datasets and their interconnections (Figure 3).

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Following these principles, portals offering access to massive amounts of data were created, such as Europeana, the European portal for Cultural Heritage, or Artresearch.net, a knowledge graph integrating data from the art photographic archives of the PHAROS association.

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Figure 3. Snapshot of the Linked Data Cloud on 02/09/2026. Source: https://lod-cloud.net/
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Ontology Modeling

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But how to create an ontology? In this blog post, we will take you through an overview of the steps to create an ontology through the concrete example of the development of the Cultural Heritage Interactions Ontology (CHint) (Baroncini & Heuvel, 2026). The aim of the ontology is to represent various types of interactions between material and immaterial cultural heritage (CH) that occur over time and space. In other words, it relates a CH object with 1) ideas and values that are relevant in the context(s) in which the object is located (i.e., a belief system), 2) the function(s) that such objects acquire in different contexts, 3) the evolution of these features over time, 4) their interaction with contextual ephemeral events and immaterial cultural heritage practices, and 5) different aspects of uncertainty related to the reconstruction of past state-of-affairs of the object.

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Before getting into details, it is important to underline that there's never a single way to model knowledge. Every model reduces infinite reality by selecting specific features. For example, the floor plan of a building does not render the 3D appearance of the building, nor does a 3D accurate scan record the temperature inside the rooms. Every model follows a specific purpose or research question, and discards a certain amount of information.

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The same happens with data modeling. Whereas \"data\" \u2013 literally, something \"given\" from the Latin word datum – is perceived as being something neutral, it always reflects a particular point of view on reality. This is particularly evident when we deal with humanities data. Not only do the branches of study reflect a worldview or way of thinking, but also the information modeled relies on often uncertain, approximate, and incomplete sources, which raise a range of subjective interpretations about the past state of affairs.

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Several methodologies can be used to develop an ontology. Among them, agile and iterative approaches, such as NeOn (Su\u00e1rez-Figueroa et al., 2015), eXtreme Design (Presutti et al., 2009), and SAMOD, are particularly relevant. Instead of modeling the whole ontology at once, the developer divides the domain into smaller areas and adds them iteratively to the main ontology. During the development of CHint, we adopted the SAMOD method (Peroni, 2016) for modular development, with the aid of the Ontology Requirements Specification Document for the initial definition of the characteristics of the overall ontology (Su\u00e1rez-Figueroa et al., 2009). For this reason, we will focus on them in the illustration of the development process.

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Define the requirements

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In the first place, the scope and aim of the project should be defined: what's the aim of the modeling? In which domain? For whom? What questions should the model be able to answer? If a domain expert and a developer are involved, these aspects should be defined together. It is a fundamental phase, as the decisions that are taken in this step shape all the following process.

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The set of needs that the model should fulfill to be considered finished is called \"requirements\". Documents such as the Ontology Requirements Specification Document (Su\u00e1rez-Figueroa et al., 2009) are useful for clarifying these characteristics. In SAMOD, however, these requirements are progressively defined and refined through a series of concrete motivating scenarios. Rather than trying to specify the whole ontology from the beginning, each iteration focuses on a specific part of the domain. Following the SAMOD method, domain experts describe a specific motivating scenario, i.e., a small, concrete description of a problem in the domain that needs to be modeled, accompanied by examples. From this scenario, the developing team formulates informal competency questions, namely, questions that the ontology should eventually be able to answer (for example, \"which subjects are represented in Botticelli's Primavera\"?).

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For the development of the Cultural Heritage Interactions Ontology, it was set that the ontology aimed to narrow the gap between records about physical cultural heritage objects (e.g., paintings, altarpieces) and manifestations of immaterial culture (e.g., a certain belief, religious events) that regard them over time and space. Such interaction can indeed deeply change the object, resulting in new functions or iconography \u2013 take into account, for example, the religious objects often musealized, appreciated more for their aesthetic value than for their religious function after their decontextualization. The scope of application is the CH sector, and it is intended to be used by digital cultural historians and/or computer scientists interested in developing applications concerning cross-cultural understanding of CH objects. The intended use of the ontology is to \"express in a machine-readable format the complex interactions between contemporary culture and immaterial events, and thoughts that eventually influenced CH objects themselves, their function and/or meaning\" (Baroncini & Heuvel, 2026, p. 14). The technical requirements were an extensive reuse of available ontologies and the formalization in OWL 2. Whereas the document was initially used to set the aim, scope, and use of the ontology, further sections were filled during the following development steps. For example, the definition of the glossary of terms, i.e., keywords relevant to the domain, depended on the theories taken into account for the definition of the domain, illustrated in the following section. Another example is the definition of competency questions, defined in the SAMOD iterations during the development. Furthermore, at this initial stage, we identified a set of requirements the ontology should address, developed in specific scenarios during\u00a0the development steps.

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From ideas to sketches: top-down and bottom-up approaches

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Figure 4. Sketches by Sofia Baroncini and Charles van den Heuvel to grasp the interaction between artworks and immaterial culture over time and space at the beginning of the development of the CHint Ontology. Copyright of the authors.
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The first important step to take is to think deeply about the domain. Depending on the cases and theories available, two main approaches (or a mix of them) are possible. The first one, top-down, consists of searching for pre-existing domain theories that model the domain and implementing them in the modeling. In this case, the developer adopts a deductive approach, and they move from the theory to the implementation. The second, opposite approach is to induce a general structure from multiple real cases, called bottom-up. For example, if there is a dataset about artworks sold in auctions, we can infer how artworks interact with the auction events and buyers from the data itself, and base the ontology on that rich example.

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In the DH domain, ontologies often rely on preexisting theories or modeling patterns to represent the domain at hand. Indeed, domain theories are already a conceptualization of the world proposed by historians, philosophers, and humanists who are or were experts in their fields. For this reason, domain theories can be an invaluable source when formalizing information. Nevertheless, theories may have their limits, as they were not at first created to be a computational model, and they reflect a socioculturally situated worldview, which may be outdated, biased, or limited to a certain culture (e.g., the Western world).

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Once the best approach has been identified, according to the available theories or data, it is a good idea to start sketching on a whiteboard or piece of paper how concepts relate to each other. Figure 4 shows the results of a first brainstorming session we had to create the CHint ontology, in which we thought about how the chosen theories could relate to each other. For the development, we have adopted a top-down approach, as we identified relevant theories concerning the evolution of time and space, frames, and the relation of works of art with a belief system.

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The importance of standards

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It is good practice to reuse existing models if they are in line with the aims of the ontology. As one of the main goals of the Semantic Web and Linked Open Data is the integration of different datasets described with a common structure, it is fundamental to identify which standards and existing ontologies can be reused for the task. Usually, standards for each domain exist, providing a backbone of how the concepts are organized in the domain. For the CH domain, the main standard is CIDOC-CRM, a conceptual framework developed and maintained by the International Council of Museums (ICOM), which serves as a structure to model museum data in different areas, from art to maritime CH. It is a good practice to reuse the standards and existing ontologies as much as possible, as they have already solved core modeling issues, making the work of the ontology developer easier and guaranteeing interoperability.

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In the CHint development, this means that existing models such as CIDOC-CRM can provide concepts that are relevant to the domain. Reusing these solutions improves interoperability and makes the resulting ontology easier to connect with other datasets.

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Draft. Test. Iterate

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Once there is an idea of the domain, scope, data, and theories available, the actual modeling can start. As cited above, many methodologies focus on the development of small portions of the ontology. Each iteration should include at least two types of testing: 1) testing the logical consistency of the ontology through a reasoner, and 2) testing the model against real data (A-BOX). This ensures that there are no logical inconsistencies and that the ontology can actually address the real-world scenario taken into account.

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\"Figure
Figure 5. Overview of the ontology development process according to SAMOD. Source: Peroni, S. (2016). https://doi.org/10.6084/M9.FIGSHARE.3189769. Licensed under CC BY 4.0
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Draft

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As introduced above, the SAMOD method1 divides the ontology into small motivating scenarios to allow agile development and focus on simpler aspects (Figure 5). Each scenario is a textual description of the area of the domain, and it is accompanied by a glossary of terms describing the core terminology of the scenario.

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For the development, we've taken into account a specific case study, chosen for its richness, as a concrete example on which the model should be tested, constituting the A-BOX of the ontology. The case concerns the relics of\u00a0 St. Servatius preserved in Maastricht, the Netherlands, which are regularly brought in procession from the 14th century to the present day. For the richness of documentation, the strong relation with the Catholic community, and the frequency with which it interacts with an immaterial cultural manifestation, it was considered a prime example for the development.

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The module Historical Frame of the CHint ontology was developed in one iteration and had one motivating scenario.

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We quote here, as a way of example, one part of the motivating scenario:

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A CH object has one or multiple contexts that are related to it. A context expresses the historical, socio-cultural situation in which an artwork exists. By definition, its delimitation is fuzzy, as it corresponds to a certain culture. It includes several traits of various natures, such as religion, social practice, taste, style, etc. Humans, and experts in art history, history, and so on, identify sets of salient traits for each context. In doing so, they frame reality in the sense of Nelson's theory to abstract such traits. In other words, they create observation frames that isolate from the reality contexts that present unifying traits. In doing so, they create a Historical Frame, which is a portion of the spacetime continuum created to better observe a context that already presents traits of unity. The traits are then collected in Reference Frames, defined according to Minsky's theory, that work as the domain pre-knowledge which is necessary for relating CH objects to their contexts (e.g., placing Raffaello's work in the Italian Renaissance).

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An object participates in one or more cultural frames, corresponding to 1) the context of artwork creation, and 2) further contexts the object traverses.

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The scenario, indeed, describes the interaction of CH objects with the socio-cultural, immaterial contexts in which they existed \u2013 either at the time of their creation, or in following situations. The glossary included key terms such as historical frame, time, event, etc.

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For this scenario, we defined Competency Questions (CQs), questions that data described with the ontology should be able to answer. For this reason, the CQs explicitly refer to the case study:

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On the basis of the motivating scenario, glossary, and CQs, the ontology engineer drafts a modelet representing how the concepts relate to each other. The design is first a sketch, which is then rendered in an OWL 2 ontology through programs for ontology editing such as Prot\u00e9g\u00e9. In this stage, the design should take into account existing standards and available modeling patterns, but without explicitly importing them. Figure 6 illustrates the modelet of the Historical Frame motivating scenario illustrated with the Graffoo representation through the program draw.io. Whereas not explicitly introduced in the modelet to lower the complexity of the task at this step, classes and relations of existing ontologies, mainly standards, were taken into account. For example, the class E92 Spacetime-Volume of CIDOC-CRM was already identified as being in line with the concept of historical frame, as it describes a portion of space and time, or the Cultural Phenomenon class of the ICON ontology, representing deep socio-cultural phenomena recognized in artworks.

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Figure 6. Modelet of the Historical Frame module of the CHint ontology. Created by Sofia Baroncini. Available at Zenodo (DOI: 10.5281/zenodo.20393679). Licensed under CC BY 4.0
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Test, iterate, and align

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After the creation of the modelet, its logical consistency should be tested through a reasoner, an operation that can be done in Prot\u00e9g\u00e9. If the test doesn't raise any error, then a small dataset of real examples described according to the model (A-BOX) needs to be created, and the logical test repeated. If no errors are raised, the Competency Questions should be translated into real SPARQL queries and performed over the dataset. If the queries give the expected result, we can merge the modelet with the main ontology developed in the previous phases.

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The last phase of each iteration is the refactoring, namely, the alignment of the current ontology with existing ones, or replacing classes and relations with equivalent or more appropriate terms from existing models. For example, during the modeling of the modelet, we previously identified the class E92 Spacetime-Volume of CIDOC-CRM as suitable to express the concept of Historical Frame, of which it could be a specification. At this stage, we make this alignment explicit, and we declare the class Historical Frame as a subclass of crm:E92. All the tests should be performed again.

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Figure 7. Aligned, final ontological representation of the Historical Frame module. Created by Sofia Baroncini. Available at Zenodo (DOI: 10.5281/zenodo.20393679). Licensed under CC BY 4.0
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The process should be iterated on all the scenarios until there are no more scenarios to be modeled. At that point, the ontology is ready to be published.

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Publishing and making the ontology FAIR

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After the ontology is developed, it is still important to make it FAIR (Findable, Accessible, Interoperable, Reusable). It is good practice to assign it a permanent URI, publish documentation, and include it in the main indexes of LOD vocabularies.

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A permanent URI can be assigned through w3id.org, whereas various tools, such as PyLode, can be used to automatically generate the documentation of the ontology from the OWL 2 file.

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In the case of CHint, a permanent ID was assigned to the ontology OWL file,\u00a0 the development and documentation, which was\u00a0created through PyLode.

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Finally, it is highly recommended to use tools such as the Ontology Pitfalls Scanner (OOPS!) and FAIR Ontology Pitfalls Scanner (FOOPS!) to detect errors or missing descriptions (e.g., labels, inverse relations) and fix the ontology accordingly before publishing it.

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Following these steps, it is possible to create a robust ontology, which can address specific domain aspects and be aligned with standards.

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References

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Baroncini, S., & van den Heuvel, C. (2026). The Historical Framing Problem: Temporal Modeling of Interactions between Tangible and Intangible Cultural Heritage. Semantic Web, 17(4), 1\u201343. https://doi.org/10.1177/22104968261454485

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Peroni, S. (2016). SAMOD: An agile methodology for the development of ontologies. Proceedings of the 13th OWL: Experiences and Directions Workshop and 5th OWL Reasoner Evaluation Workshop (OWLED-ORE 2016). https://doi.org/10.6084/M9.FIGSHARE.3189769

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Presutti, V., Daga, E., Gangemi, A., & Blomqvist, E. (2009). eXtreme Design with Content Ontology Design Patterns. Proceedings of the 2009 International Conference on Ontology Patterns, 516, 83\u201397. https://ceur-ws.org/Vol-516/pap21.pdf

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Su\u00e1rez-Figueroa, M. C., G\u00f3mez-P\u00e9rez, A., & Fern\u00e1ndez-L\u00f3pez, M. (2015). The NeOn Methodology framework: A scenario-based methodology for ontology development. Applied Ontology, 10(2), 107\u2013145. https://doi.org/10.3233/AO-150145

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Su\u00e1rez-Figueroa, M., Gomez-Perez, A., & Villazon Terrazas, B. (2009). How to Write and Use the Ontology Requirements Specification Document. On the Move to Meaningful Internet Systems: OTM 2009: Confederated International Conferences, CoopIS, DOA, IS, and ODBASE 2009, Vilamoura, Portugal, November 1-6, 2009, Proceedings, 2, 966\u2013982. https://doi.org/10.1007/978-3-642-05151-7_16

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Featured image: Sketches by Sofia Baroncini and Charles van den Heuvel to grasp the interaction between artworks and immaterial culture over time and space at the beginning of the development of the CHint Ontology. Copyright of the authors.

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  1. This blog post provides just a general overview of the process to make the methodology more accessible and understandable. For a complete and detailed overview of the modeling process, refer to Peroni (2016). [↩]
    2. \n
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Jente Houweling published her first PhD thesis chapter earlier this year:\n\"ToxTempAssistant: using large language models to standardise cell-based toxicological test method descriptions\"\n(doi:10.1080/2833373X.2026.2638036). So far, I have been blogging about\nmany of the articles on which I am (co-)author. To put it in context. To reflect on the work. I have been postponing\nwriting about this paper because there is a lot to reflect on. I will pick out two things. First, I look at the use\nof AI. The second is the unique, innovatie publishing model of the journal where the article was published.\nIf you want to just see it in action, ToxTempAssistant is running\non the Virtual Human Platform for safety assessment.

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Before we go there, just a quick note on what ToxTemps are and ToxTempAssistent actually is:

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The ToxTemp template, based on OECD Guidance Document 211, standardises reporting for cell-based NAMs. However,\ncompleting its 77 questions constitutes a substantial bottleneck. The aim of this study is to introduce ToxTempAssistant,\na Large Language Model (LLM)-assisted web tool that supports toxicologists in drafting ToxTemp documents based on\nuser-supplied context documents. This study quantifies the tool's baseline performance under controlled conditions.\nToxTempAssistant uses grounded, per-question prompting with mandatory source attribution.

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The LLM aspects

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AI is very old. Arguably, my PhD thesis\nhad this as key topic, though I prefered to use to term chemometric or machine learning.\nCritial thinking has been essential to this field for a long time, and much of the PhD thesis is actually\nabout critically assessing the performance of the methods used in the thesis. There is decades of research\nhow you do this. Sadly, when it comes to Large Language Models (LLMs), these are not routinely used.

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LLMs are indeed something new. I have seen natural language processing\nresearch when I was Cambridge with Peter Murray-Rust. The current LLMs are different, less deterministic, more probabilistic.\nFrom a chemometrics perspective, that makes sense. Language is complex, and not so deterministic in itself. Moreover,\nwhen representing words, sentences as numbers, you can integrate any resource (think data tables, images, etc). Even more,\ndigital representation was even more the central theme of my PhD thesis.

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But because of the nature of the method, the nature of how the commercial, better known models are trained (and the\nimpact on the notion of copyright), the impact on the climate emergency,\nthe black box that these LLMs often are, there are so many technical, scientific, and ethical reasons to stay away from them.

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You can write books about that. Literally (I did not read them yet):

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(I have the feeling I am missing one title I wanted to highlight. If I remember, I will add it.)

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And more here and here.\nAnd I am looking forward to reading Deep Unlearning: The Rise of AI and the Radicalization of a Tech Idealist.\nAlso, I recommend at least following Timnit Gebru and\nEmily Bender.

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A year ago, I signed the Open Letter: Stop the Uncritical Adoption of AI Technologies in Academia,\nnow signed by more than 2,000 people (it is not too late).

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So, with all these things mind, I am happy that Jente did critically adopt LLMs in her work. The paper includes\nvarious experiments to explore the impact of various model parameters on generating nonsense. She also explored\nto use of alternative LLMs platforms, opening the option that some day it runs on other, more ethical platforms.\nToxTempAssistant, moreover, limits the material it takes information from, from a limited set of sources, provided\nby the users. Of course, the model itself is still training on resources with questionable provenance.

\n

Jente's paper describes the use of positive and negative controls to put the performance in perspective.\nIn doing so, the paper formalizes how to evaluate the use of LLMs in situations where the LLM is used\nto summarize other reports, a common thing to do. This allows us to monitor the impact of, for example,\nnew LLM releases.

\n

The results are promising and various independent projects have shown interest in adoption. The ToxTemp\nreports are important for safety assessment: they provide essential context to experimental results and\nas such essential to the FAIR-ness of toxicology data.

\n

Open Peer Review

\n

The ToxTempAssistant paper is published in the relatively new journal Evidence-Based Toxicology (EBT):

\n
\n

Evidence-Based Toxicology is a broad-focus, gold open-access journal, created to support the use of open science practices and\nevidence-based methods in toxicology and environmental health.

\n
\n

So, CC-BY license (gold open access) and support for Open Science. And Open Peer Review, as we will see. Also,\nI undestand it is not a diamond open access journal, so expect APCs.

\n

The journal has a community on Zenodo for preprints and peer-reviews.\nI think this is a really nice choice. Of course, a journal specific preprint server has downsides too. For example,\nif it gets rejected from EBT, do you use the EBT preprint server when submitting to another journal? Do you upload\na new version (after all, you should address some of the comments why it was rejected) to another preprint server?

\n

The EBT preprint gets a record and revisions are uploaded as new versions to the same Zenodo record\n(doi10.5281/zenodo.17192970):

\n

\"\"

\n

But because EBT uses open peer review, there is a parallel Zenodo entry with the reviews\n(doi10.5281/zenodo.17278785):

\n

\"\"

\n

The last version here is the acceptance notice:

\n

\"\"

\n

One of the reviewer suggestions was to use the TRIPOD-LLM template\n(doi:10.1038/s41591-024-03425-5), which was included in a\nlater revision. That made a lot of sense and is a nice example how the journal actively works\non applying open science ideas. The journal webpage writes:

\n
\n

We define \"open science\" as the set of practices aimed at improving the transparency, validity,\nreproducibility, and accessibility of scientific research, while promoting equality of\nopportunity to participate in and benefit from the products of said research.

\n
\n

One comment here is that the template asks on what page that point of the checklist is discussed\nin the article. That is nice, but links it directly to the revision of the manuscript that\nform applies too, but that is not reported in the template. Not ideal. Then again, the point\nis the checking, so maybe not a big deal.

\n

Another comment is that it seems the journal website's page for the article does not seem to actually\nlink to the preprints nor the peer-review reports (or acceptance note). So, in time, these\nopen science aspects of this article will likely get lost in time. Who will find those reports\nif the article does not cite them? This will require Taylor&Francis to modernize the publishing\nmodel, and I sincerly doubt that that will ever happen.

\n

Prof. Anne Kienhuis, one of the co-authors, suggested\nthis journal lead by Prof. Paul Whaley.\nAnd I am happy to have seen this new approach in action and like to thank Paul for pushing for\nthese innovations. I recommend trying it yourself for your next toxicology work.

\n

References

\n
\n
Gallifant, J., Afshar, M., Ameen, S., Aphinyanaphongs, Y., Chen, S., Cacciamani, G., Demner-Fushman, D., Dligach, D., Daneshjou, R., Fernandes, C., Hansen, L. H., Landman, A., Lehmann, L., McCoy, L. G., Miller, T., Moreno, A., Munch, N., Restrepo, D., Savova, G., \u2026 Bitterman, D. S. (2025). The TRIPOD-LLM reporting guideline for studies using large language models. Nature Medicine, 31(1), 60\u201369. https://doi.org/10.1038/s41591-024-03425-5 [cito:discusses] CrossRef Scholia
\n
Houweling, J. (Johanne) M., Arras, M. M., Willighagen, E., Kienhuis, A., Jennen, D., & Evelo, C. (2026). ToxTempAssistant: Using Large Language Models to Standardise Cell-Based Toxicity Test Method Descriptions. Zenodo. https://doi.org/10.5281/ZENODO.17192970 [cito:citesAsEvidence] CrossRef Scholia
\n
Houweling, J. M., Arras, M. M. L., Willighagen, E. L., Jennen, D. G. J., Evelo, C. T., & Kienhuis, A. S. (2026). ToxTempAssistant\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u202f: using large language models to standardise cell-based toxicological test method descriptions. Evidence-Based Toxicology, 4(1). https://doi.org/10.1080/2833373x.2026.2638036 [cito:discusses] CrossRef Scholia
\n
Krebs, A., Waldmann, T., Wilks, M. F., van Vugt-Lussenburg, B. M. A., van der Burg, B., Terron, A., Steger-Hartmann, T., Ruegg, J., Rovida, C., Pedersen, E., Pallocca, G., Luijten, M., Leite, S. B., Kustermann, S., Kamp, H., Hoeng, J., Hewitt, P., Herzler, M., Hengstler, J. G., \u2026 Leist, M. (2019). https://www.altex.org/index.php/altex/article/view/1339. ALTEX, 682\u2013699. https://doi.org/10.14573/altex.1909271 [cito:citesForInformation] CrossRef Scholia
\n
Whaley, P. (2026). Evaluation Reports for TEBT-2025-0014 | Houweling et al. Zenodo. https://doi.org/10.5281/ZENODO.17278785 [cito:citesAsEvidence] CrossRef Scholia
\n
","doi":"https://doi.org/10.59350/v5ehk-42y77","guid":"https://doi.org/10.59350/v5ehk-42y77","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790985600,"reference":[{"id":"https://doi.org/10.1080/2833373x.2026.2638036","unstructured":"Houweling, J. M., Arras, M. M. L., Willighagen, E. L., Jennen, D. G. J., Evelo, C. T., & Kienhuis, A. S. (2026). ToxTempAssistant : using large language models to standardise cell-based toxicological test method descriptions. Evidence-Based Toxicology, 4(1). [cito:discusses]"},{"id":"https://doi.org/10.14573/altex.1909271","unstructured":"Krebs, A., Waldmann, T., Wilks, M. F., van Vugt-Lussenburg, B. M. A., van der Burg, B., Terron, A., Steger-Hartmann, T., Ruegg, J., Rovida, C., Pedersen, E., Pallocca, G., Luijten, M., Leite, S. B., Kustermann, S., Kamp, H., Hoeng, J., Hewitt, P., Herzler, M., Hengstler, J. G., \u2026 Leist, M. (2019). https://www.altex.org/index.php/altex/article/view/1339. ALTEX, 682\u2013699. [cito:citesForInformation]"},{"id":"https://doi.org/10.5281/zenodo.17278785","unstructured":"Whaley, P. (2026). Evaluation Reports for TEBT-2025-0014 | Houweling et al.. Zenodo. [cito:citesAsEvidence]"},{"id":"https://doi.org/10.5281/zenodo.17192970","unstructured":"Houweling, J. (Johanne) M., Arras, M. M., Willighagen, E., Kienhuis, A., Jennen, D., Evelo, C., Arras, M. M., Jennen, D., Willighagen, E., Evelo, C., & Kienhuis, A. (2026). ToxTempAssistant: Using Large Language Models to Standardise Cell-Based Toxicity Test Method Descriptions. [cito:citesAsEvidence]"},{"id":"https://doi.org/10.1038/s41591-024-03425-5","unstructured":"Gallifant, J., Afshar, M., Ameen, S., Aphinyanaphongs, Y., Chen, S., Cacciamani, G., Demner-Fushman, D., Dligach, D., Daneshjou, R., Fernandes, C., Hansen, L. H., Landman, A., Lehmann, L., McCoy, L. G., Miller, T., Moreno, A., Munch, N., Restrepo, D., Savova, G., \u2026 Bitterman, D. S. (2025). The TRIPOD-LLM reporting guideline for studies using large language models. Nature Medicine, 31(1), 60\u201369. [cito:discusses]"}],"rid":"pn95g-v4h02","summary":"Jente Houweling published her first PhD thesis chapter earlier this year: \"ToxTempAssistant: using large language models to standardise cell-based toxicological test method descriptions\" (doi:10.1080/2833373X.2026.2638036). So far, I have been blogging about many of the articles on which I am (co-)author. To put it in context. To reflect on the work.","tags":["Fair","Llm","Vhp4safety","Openscience"],"title":"New paper: \"ToxTempAssistant: using large language models to standardise cell-based toxicological test method descriptions\"","updated_at":1791016505,"url":"https://chem-bla-ics.linkedchemistry.info/2026/10/03/new-paper-toxtempassistant-using-large-language-models-to-standardise-cell-based-toxicological-test-method-descriptions.html","version":"v1"}},{"document":{"authors":[{"affiliation":[{"name":"Imperial College London, Chemstry"}],"contributor_roles":[],"family":"Rzepa","given":"Henry","url":"https://orcid.org/0000-0002-8635-8390"}],"blog":{"authors":[{"name":"Henry Rzepa","url":"https://orcid.org/0000-0002-8635-8390"}],"community_id":"8fb94c86-e95f-41cf-aac2-a2877ffc1b5f","created":1693094400,"current_feed_url":null,"description":"Chemistry with a twist","doi":"https://doi.org/10.59350/rzepa","favicon":"https://rogue-scholar.org/api/communities/8fb94c86-e95f-41cf-aac2-a2877ffc1b5f/logo","feed_format":"application/atom+xml","feed_url":"https://www.ch.ic.ac.uk/rzepa/blog/?feed=atom","filter":null,"generator":"WordPress","home_page_url":"https://www.ch.ic.ac.uk/rzepa/blog","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"rzepa","status":"active","subfield":"1606","title":"Henry Rzepa's Blog","updated":1791013525,"use_api":true},"blog_name":"Henry Rzepa's Blog","blog_slug":"rzepa","content_html":"
\n

Metalla-aromatics have been defined as metallacycles that are derived from the formal replacement of a carbon atom in the framework of an organic aromatic ring with a metal fragment.[1]. Here I explore whether this simple definition can be broadened to sulfur-nitrogen rings which contain few[2],[3] if indeed any[4],[5],[6],[7] carbon atoms and which also happen to be planar aromatic molecules.

\n

Prologue

\n

Our story starts with the authors of this article[8] reporting the formation of the sulfur-nitrogen titanacycles 1[9] and 2[10] (green in the scheme 1 below) from Cp2Ti(CO)2 reacting with S4N4. Isolating compound 2 was something of a surprise, since they had been expecting/hoping to get 3[11] instead (red in scheme 3 below). This result was unexplained in the article and unremarked upon by anyone else since.

\n

\"\"
\nScheme 1. Formed products 1 – 2\u00a0from the reaction of Cp2Ti(CO)2 with S4N4.

\n

To develop the prologue, we start with compound 7 (Scheme 2) which was described[3] as a (H\u00fcckel-class) 10 \u03c0-aromatic ring (6e from double bonds, 4e from S lone pairs) containing one ring carbon atom and represented in the original paper as 7a. In fact, NBO7 analysis[12],[13]\u2021 (as obtained with no 3-centre bonds allowed) suggests that 7b is a more accurate representation (4e from two \u03c0-double bonds and 6e from lone pairs = 10\u03c0 =4n+2, n=2 ). Molecule 7b\u00a0has a computed NICS(0) (= Nucleus Independent Chemical Shift at ring centroid) value of -9.6 ppm,[14] NICS here being used as an approximate indicator of aromaticity\u00a0(or lack of it),\u00a0with e.g. the archetypal 4n+2 (n=1) \u03c0-aromatic benzene giving a NICS(0) value of ~-10. For 4n/4n+2 aromaticity selection rules, see e.g. [15],[16]
\n\"\"
\nScheme 2. Compounds 7a/b\u00a0and 7c.

\n

A replacement of the carbon and its attached ester group according to the definition above by using (Cp.CO)Ti as a transition metal results in e.g. 7c – a compound not dissimilar to the compound discussed in the previous post[17]. A MN15L/Def2-TZVPP calculation[18] gives the geometry shown in Figure 1. A NBO7[12] localisation procedure\u2021 gives the result[19] shown as 7c (Scheme 2, Figure 2), with back bonding into titanium d-orbitals and the three \u03c0-bonds and two lone pairs (one N, one S) resulting in a total of ten cyclically conjugated \u03c0-electrons.

\n

\"\"
\nFigure 1. Calculated\u00a0MN15L/Def2-TZVPP/SCRF=DCM structure of compound 7c.

\n

\"\"

\n

Figure 2. Five NBO7 localised orbitals representing 7c.

\n

A NICS(0) NMR estimate of the aromaticity for 7c gives an antiaromatic value of +9.8 ppm,[20], and\u00a0hence tending to M\u00f6bius antiaromaticity according to the selection rules for 4n+2 (n=2) electrons.[15],[16] This combination of 4n+2 (n=2) conjugated \u03c0-electrons and NMR-based antiaromaticity allows one to infer that there must be one orbital phase shift in the conjugated \u03c0-electrons, presumably at either the Ti=S centre or the Ti=N centre but not both. This pair of calculations provides an interesting and useful prologue to and calibration of the NICS(0) procedure as an (anti)aromaticity metric in such systems.

\n

Discussion. Molecule 1.

\n

CASZOL10 (molecule 1, scheme 1, Figure 3), has an NBO7\u2021 Lewis localised structure[21]\u00a0shown as 1a rather than the literature representation 1[8] (Scheme 1, Figure 4). As with 7c, it comprises three \u03c0-bonds and two lone pairs (one N, one S). In contrast to 7c, the NICS(0) = -6.7[22] suggests moderate aromatic character, which as a 10 \u03c0-electron aromatic must have either no phase shifts or two. It suggests that, as informed by 7c, the Ti=N bond does not contribute any phase shifts. On the basis of these results, we suggest that molecule 1 can be described as a H\u00fcckel type (4n+2) moderately aromatic inorganic metallacycle.

\n

\"\"
\nFigure 3. Calculated structure of 1, CASZOL10. The purple point is the NICS probe.

\n

\"\"
\nFigure 4. Five NBO7 localised orbitals representing 1a (total NBO7 orbital occupancy 8.39e)

\n

Discussion. Molecule 2.

\n

Molecule 2 (CIWFIX10, Figure 5) has NICS(0) = -6.0 ppm[23] for 8\u03c0 electrons (one NBO7 double bond and three NBO7 lone pairs[24]) represented as 2a in scheme 1 (Figure 5).

\n

\"\"
\nFigure 5. Structure of 2,\u00a0CIWFIX10. The purple point is the NICS atom.

\n

\"\"

\n

Figure 6. Four NBO7 localised orbitals representing 2b (total NBO orbital occupancy 6.92e).

\n

The moderate NMR-based aromaticity for a 4n (n=2) electron cycle implies M\u00f6bius character, [15],[16] whereby significant twisting of the adjacent sulfur-nitrogen ring orbitals allows a phase shift to occur via an unoccupied Ti d-orbital (Figure 7).

\n

\"\"
\n

\n

Discussion. Unformed Compounds (Scheme3).

\n

\"\"

\n

Scheme\u00a03. Unformed compounds 3–6 from the reaction shown in Scheme 1.

\n

Compounds 3-6 are all computed as higher in free energy than 2. Compound 3a (mysteriously not formed in the original report[8]) is +13.7 kcal/mol higher than 2, and clearly non-aromatic (NICS(0) = -0.29 ppm). \u00a0This may be because the ring is relatively flat and not capable of the twisting required to become M\u00f6bius aromatic, something that was possible in 2.[25],[26],[27] Compound 4 (orange in scheme) is interesting since it is only 3.9 kcal/mol higher than 2 and having 8\u03c0 electrons (two bonds, two lone pairs) has a NICS(0) of -8.4 ppm[28] appropriate for a M\u00f6bius metallaaromatic and again has a ring capable of the required twisting as per 2. It might be synthesizable if formed by a different method.

\n

Conclusions

\n

Both 1 and 2 are suggested here as examples of inorganic metallaaromatics, respectively of the H\u00fcckel and M\u00f6bius type,[15],[16] and uniquely with no carbon atoms present in the aromatic ring – a hitherto unrecognised class of aromatic molecule. We here argue that the non-formation of compound 3 as indicated in original article[8] is because it is non-metalla-aromatic, and in its place compound 2 is formed precisely because it IS likely to be metalla-aromatic. It is our expectation that many more such inorganic metalla-aromatics could exist.

\n
\n

\u2021Use of the older NBO3 procedure is deprecated here, since it is prone to converging for these types of systems to unphysical solutions. We have established that the essential character of the NBO7 orbitals does not depend on the quality of the basis set used[29] or the DFT procedure (albeit tested only for one additional functional, \u03c9B97XD[30],[31]).

\n
\n

This post has DOI: 10.59350/dsyea-mrq85

\n

References

\n
  1. D. Chen, Y. Hua, and H. Xia, \"Metallaaromatic Chemistry: History and Development\", Chemical Reviews, vol. 120, pp. 12994-13086, 2020. https://doi.org/10.1021/acs.chemrev.0c00392\n\n
    2. \n
  2. R. Jones, J.L. Morris, A.W. Potts, C.W. Rees, D.J. Rigg, H.S. Rzepa, and D.J. Williams, \"Electronic and crystallographic structures of trithiadiazepines\", Journal of the Chemical Society, Chemical Communications, pp. 398, 1985. https://doi.org/10.1039/c39850000398\n\n
    3. \n
  3. S.T.A.K. Daley, C.W. Rees, and D.J. Williams, \"1,3,5,2,4-Trithiadiazepines and 1,3,5,2,4,6-trithiatriazepines, new 10? heteroaromatic systems\", Journal of the Chemical Society, Chemical Communications, pp. 55, 1984. https://doi.org/10.1039/c39840000055\n\n
    4. \n
  4. P.N. Jagg, P.F. Kelly, H.S. Rzepa, D.J. Williams, J.D. Woollins, and W. Wylie, \"The preparation, X-ray crystal structure and theoretical study of [CoCp\n <sub>2</sub>\n ][S\n <sub>3</sub>\n N\n <sub>3</sub>\n ], (Cp = cyclopentadienyl), a novel stacking compound incorporating multiple C\u2013H \u22ef N(p\n <sub>\u03c0</sub>\n ) interactions\", J. Chem. Soc., Chem. Commun., vol. 0, pp. 942-944, 1991. https://doi.org/10.1039/c39910000942\n\n
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  7. T. Chivers, and R.S. Laitinen, \"Chalcogen\u2013Nitrogen Chemistry\", 2021. https://doi.org/10.1142/12397\n\n
    8. \n
  8. C.G. Marcellus, R.T. Oakley, W.T. Pennington, and A.W. Cordes, \"Titanium sulfur nitrogen heterocycles: preparation and molecular structures of titanocene trisulfur tetranitride (.eta.5-C5H5)2TiS3N4 and titanocene trisulfur dinitride (.eta.5-C5H5)2TiS3N2\", Organometallics, vol. 5, pp. 1395-1400, 1986. https://doi.org/10.1021/om00138a016\n\n
    9. \n
  9. H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP G = -2649.576493\", 2026. https://doi.org/10.5281/zenodo.22195764\n\n
    10. \n
  10. H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67\", 2026. https://doi.org/10.5281/zenodo.22199646\n\n
    11. \n
  11. H. Rzepa, \"Cp2TiS3N2, MN15L/Def2-TZVPP G = -2540.173075\", 2026. https://doi.org/10.5281/zenodo.22193016\n\n
    12. \n
  12. E.D. Glendening, C.R. Landis, and F. Weinhold, \"<i>NBO 7.0</i>\n : New vistas in localized and delocalized chemical bonding theory\", Journal of Computational Chemistry, vol. 40, pp. 2234-2241, 2019. https://doi.org/10.1002/jcc.25873\n\n
    13. \n
  13. H. Rzepa, \"Reees 8 (MOs) NBO\", 2026. https://doi.org/10.5281/zenodo.22874369\n\n
    14. \n
  14. H. Rzepa, \"Reees 8 (MOs) NMR Bq\", 2026. https://doi.org/10.5281/zenodo.22876817\n\n
    15. \n
  15. H.S. Rzepa, \"M\u00f6bius Aromaticity and Delocalization\", Chemical Reviews, vol. 105, pp. 3697-3715, 2005. https://doi.org/10.1021/cr030092l\n\n
    16. \n
  16. P.L. Ayers, R.J. Boyd, P. Bultinck, M. Caffarel, R. Carb\u00f3-Dorca, M. Caus\u00e1, J. Cioslowski, J. Contreras-Garcia, D.L. Cooper, P. Coppens, C. Gatti, S. Grabowsky, P. Lazzeretti, P. Macchi, ?. Mart\u00edn Pend\u00e1s, P.L. Popelier, K. Ruedenberg, H. Rzepa, A. Savin, A. Sax, W.E. Schwarz, S. Shahbazian, B. Silvi, M. Sol\u00e0, and V. Tsirelson, \"Six questions on topology in theoretical chemistry\", Computational and Theoretical Chemistry, vol. 1053, pp. 2-16, 2015. https://doi.org/10.1016/j.comptc.2014.09.028\n\n
    17. \n
  17. H. Rzepa, \"Exploring the effect that causes ring-size specificity of transition metals for polysulfide dianions: Cyclopentadienyl-2,6-di-isopropylphenoxy Titanium pentasulfide.\", 2026. https://doi.org/10.59350/6hj5w-5w040\n\n
    18. \n
  18. H. Rzepa, \"CpCOTiS3N3 (from Rees system)\", 2026. https://doi.org/10.5281/zenodo.22869370\n\n
    19. \n
  19. H. Rzepa, \"CpCOTiS3N3 (from Rees system) Compound 7c NBO7\", 2026. https://doi.org/10.5281/zenodo.23061061\n\n
    20. \n
  20. H. Rzepa, \"CpCOTiS3N3 (from Rees system) NMR Bq Isotropic = -9.8464\", 2026. https://doi.org/10.5281/zenodo.22869771\n\n
    21. \n
  21. H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP Compound 1b, G = -2649.576493 NBO7\", 2026. https://doi.org/10.5281/zenodo.22934627\n\n
    22. \n
  22. H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP G = -2649.576493 NMR Bq Isotropic = 6.6460\", 2026. https://doi.org/10.5281/zenodo.22232235\n\n
    23. \n
  23. H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67 NMR Bq Isotropic = 6.0085\", 2026. https://doi.org/10.5281/zenodo.22225961\n\n
    24. \n
  24. H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67 Compound 2 NBO7\", 2026. https://doi.org/10.5281/zenodo.23018389\n\n
    25. \n
  25. H.S. Rzepa, \"A Double-Twist M\u00f6bius-Aromatic Conformation of [14]Annulene\", Organic Letters, vol. 7, pp. 4637-4639, 2005. https://doi.org/10.1021/ol0518333\n\n
    26. \n
  26. H.S. Rzepa, \"Lemniscular Hexaphyrins as Examples of Aromatic and Antiaromatic Double-Twist M\u00f6bius Molecules\", Organic Letters, vol. 10, pp. 949-952, 2008. https://doi.org/10.1021/ol703129z\n\n
    27. \n
  27. S.M. Rappaport, and H.S. Rzepa, \"Intrinsically Chiral Aromaticity. Rules Incorporating Linking Number, Twist, and Writhe for Higher-Twist M\u00f6bius Annulenes\", Journal of the American Chemical Society, vol. 130, pp. 7613-7619, 2008. https://doi.org/10.1021/ja710438j\n\n
    28. \n
  28. H. Rzepa, \"Cp2TiSNNSS MN15L/Def2-TZVPP, G = -2540.188689 NMR Bq Isotropic = 8.3780\", 2026. https://doi.org/10.5281/zenodo.22830870\n\n
    29. \n
  29. H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-QZVPP Compound 1b, G = -2649.576493 NBO (not 7)\", 2026. https://doi.org/10.5281/zenodo.22933586\n\n
    30. \n
  30. H. Rzepa, \"Cp2TiS3N4, wB97XD/Def2-TZVPP Compound 1b, G = -2649.576493 NBO (not 7)\", 2026. https://doi.org/10.5281/zenodo.23034010\n\n
    31. \n
  31. H. Rzepa, \"Cp2TiS3N4, wB97XD/Def2-TZVPP Compound 1b, G = -2649.576493 NBO7\", 2026. https://doi.org/10.5281/zenodo.23039008\n\n
    32. \n
\n\n
","doi":"https://doi.org/10.59350/dsyea-mrq85","guid":"https://www.ch.ic.ac.uk/rzepa/blog/?p=32123","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790985600,"reference":[{"id":"https://doi.org/10.1021/acs.chemrev.0c00392","unstructured":"D. Chen, Y. Hua, and H. Xia, \"Metallaaromatic Chemistry: History and Development\", Chemical Reviews, vol. 120, pp. 12994-13086, 2020."},{"id":"https://doi.org/10.1039/c39850000398","unstructured":"R. Jones, J.L. Morris, A.W. Potts, C.W. Rees, D.J. Rigg, H.S. Rzepa, and D.J. Williams, \"Electronic and crystallographic structures of trithiadiazepines\", Journal of the Chemical Society, Chemical Communications, pp. 398, 1985."},{"id":"https://doi.org/10.1039/c39840000055","unstructured":"S.T.A.K. Daley, C.W. Rees, and D.J. Williams, \"1,3,5,2,4-Trithiadiazepines and 1,3,5,2,4,6-trithiatriazepines, new 10? heteroaromatic systems\", Journal of the Chemical Society, Chemical Communications, pp. 55, 1984."},{"id":"https://doi.org/10.1039/c39910000942","unstructured":"P.N. Jagg, P.F. Kelly, H.S. Rzepa, D.J. Williams, J.D. Woollins, and W. Wylie, \"The preparation, X-ray crystal structure and theoretical study of [CoCp 2 ][S 3 N 3 ], (Cp = cyclopentadienyl), a novel stacking compound incorporating multiple C\u2013H \u22ef N(p \u03c0 ) interactions\", J. Chem. Soc., Chem. Commun., vol. 0, pp. 942-944, 1991."},{"id":"https://doi.org/10.1002/cber.19951280103","unstructured":"A. Haas, and M. Pryka, \"New Pathways in Tellurium\u2010Chalkogen\u2010Nitrogen Chemistry: Preparations, Structures, and Properties of Telluraheterocycles\", Chemische Berichte, vol. 128, pp. 11-22, 1995."},{"id":"https://doi.org/10.1016/0277-5387(96)00223-9","unstructured":"J. Galan-Mascaros, A.M. Slawin, J. Derek Woollins, and D.J. Williams, \"\u03c0-facial interactions between Cl\u2212 and [S4N3]+. X-ray crystal structure of [S4N3]Cl\", Polyhedron, vol. 15, pp. 4603-4605, 1996."},{"id":"https://doi.org/10.1142/12397","unstructured":"T. Chivers, and R.S. Laitinen, \"Chalcogen\u2013Nitrogen Chemistry\", 2021."},{"id":"https://doi.org/10.1021/om00138a016","unstructured":"C.G. Marcellus, R.T. Oakley, W.T. Pennington, and A.W. Cordes, \"Titanium sulfur nitrogen heterocycles: preparation and molecular structures of titanocene trisulfur tetranitride (.eta.5-C5H5)2TiS3N4 and titanocene trisulfur dinitride (.eta.5-C5H5)2TiS3N2\", Organometallics, vol. 5, pp. 1395-1400, 1986."},{"id":"https://doi.org/10.5281/zenodo.22195764","unstructured":"H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP G = -2649.576493\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22199646","unstructured":"H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22193016","unstructured":"H. Rzepa, \"Cp2TiS3N2, MN15L/Def2-TZVPP G = -2540.173075\", 2026."},{"id":"https://doi.org/10.1002/jcc.25873","unstructured":"E.D. Glendening, C.R. Landis, and F. Weinhold, \"NBO 7.0 : New vistas in localized and delocalized chemical bonding theory\", Journal of Computational Chemistry, vol. 40, pp. 2234-2241, 2019."},{"id":"https://doi.org/10.5281/zenodo.22874369","unstructured":"H. Rzepa, \"Reees 8 (MOs) NBO\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22876817","unstructured":"H. Rzepa, \"Reees 8 (MOs) NMR Bq\", 2026."},{"id":"https://doi.org/10.1021/cr030092l","unstructured":"H.S. Rzepa, \"M\u00f6bius Aromaticity and Delocalization\", Chemical Reviews, vol. 105, pp. 3697-3715, 2005."},{"id":"https://doi.org/10.1016/j.comptc.2014.09.028","unstructured":"P.L. Ayers, R.J. Boyd, P. Bultinck, M. Caffarel, R. Carb\u00f3-Dorca, M. Caus\u00e1, J. Cioslowski, J. Contreras-Garcia, D.L. Cooper, P. Coppens, C. Gatti, S. Grabowsky, P. Lazzeretti, P. Macchi, ?. Mart\u00edn Pend\u00e1s, P.L. Popelier, K. Ruedenberg, H. Rzepa, A. Savin, A. Sax, W.E. Schwarz, S. Shahbazian, B. Silvi, M. Sol\u00e0, and V. Tsirelson, \"Six questions on topology in theoretical chemistry\", Computational and Theoretical Chemistry, vol. 1053, pp. 2-16, 2015."},{"id":"https://doi.org/10.59350/6hj5w-5w040","unstructured":"H. Rzepa, \"Exploring the effect that causes ring-size specificity of transition metals for polysulfide dianions: Cyclopentadienyl-2,6-di-isopropylphenoxy Titanium pentasulfide.\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22869370","unstructured":"H. Rzepa, \"CpCOTiS3N3 (from Rees system)\", 2026."},{"id":"https://doi.org/10.5281/zenodo.23061061","unstructured":"H. Rzepa, \"CpCOTiS3N3 (from Rees system) Compound 7c NBO7\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22869771","unstructured":"H. Rzepa, \"CpCOTiS3N3 (from Rees system) NMR Bq Isotropic = -9.8464\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22934627","unstructured":"H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP Compound 1b, G = -2649.576493 NBO7\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22232235","unstructured":"H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP G = -2649.576493 NMR Bq Isotropic = 6.6460\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22225961","unstructured":"H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67 NMR Bq Isotropic = 6.0085\", 2026."},{"id":"https://doi.org/10.5281/zenodo.23018389","unstructured":"H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67 Compound 2 NBO7\", 2026."},{"id":"https://doi.org/10.1021/ol0518333","unstructured":"H.S. Rzepa, \"A Double-Twist M\u00f6bius-Aromatic Conformation of [14]Annulene\", Organic Letters, vol. 7, pp. 4637-4639, 2005."},{"id":"https://doi.org/10.1021/ol703129z","unstructured":"H.S. Rzepa, \"Lemniscular Hexaphyrins as Examples of Aromatic and Antiaromatic Double-Twist M\u00f6bius Molecules\", Organic Letters, vol. 10, pp. 949-952, 2008."},{"id":"https://doi.org/10.1021/ja710438j","unstructured":"S.M. Rappaport, and H.S. Rzepa, \"Intrinsically Chiral Aromaticity. Rules Incorporating Linking Number, Twist, and Writhe for Higher-Twist M\u00f6bius Annulenes\", Journal of the American Chemical Society, vol. 130, pp. 7613-7619, 2008."},{"id":"https://doi.org/10.5281/zenodo.22830870","unstructured":"H. Rzepa, \"Cp2TiSNNSS MN15L/Def2-TZVPP, G = -2540.188689 NMR Bq Isotropic = 8.3780\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22933586","unstructured":"H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-QZVPP Compound 1b, G = -2649.576493 NBO (not 7)\", 2026."},{"id":"https://doi.org/10.5281/zenodo.23034010","unstructured":"H. Rzepa, \"Cp2TiS3N4, wB97XD/Def2-TZVPP Compound 1b, G = -2649.576493 NBO (not 7)\", 2026."},{"id":"https://doi.org/10.5281/zenodo.23039008","unstructured":"H. Rzepa, \"Cp2TiS3N4, wB97XD/Def2-TZVPP Compound 1b, G = -2649.576493 NBO7\", 2026."}],"rid":"63h5p-zx280","summary":"Metalla-aromatics have been defined as metallacycles that are derived from the formal replacement of a carbon atom in the framework of an organic aromatic ring with a metal fragment.. Here I explore whether this simple definition can be broadened to sulfur-nitrogen rings which contain few, if indeed any,,, carbon atoms and which also happen to [\u2026]","tags":["Interesting Chemistry"],"title":"Unrecognised inorganic metalla-aromatic rings? The mystery of (cyclo-N,S)-titanocenes.","updated_at":1791013684,"url":"https://www.ch.ic.ac.uk/rzepa/blog/?p=32123","version":"v1"}},{"document":{"authors":[{"affiliation":[{"name":"Imperial College London, Chemistry"}],"contributor_roles":[],"family":"Rzepa","given":"Henry","url":"https://orcid.org/0000-0002-8635-8390"}],"blog":{"authors":[{"name":"Henry Rzepa","url":"https://orcid.org/0000-0002-8635-8390"}],"community_id":"8fb94c86-e95f-41cf-aac2-a2877ffc1b5f","created":1693094400,"current_feed_url":null,"description":"Chemistry with a twist","doi":"https://doi.org/10.59350/rzepa","favicon":"https://rogue-scholar.org/api/communities/8fb94c86-e95f-41cf-aac2-a2877ffc1b5f/logo","feed_format":"application/atom+xml","feed_url":"https://www.ch.ic.ac.uk/rzepa/blog/?feed=atom","filter":null,"generator":"WordPress","home_page_url":"https://www.ch.ic.ac.uk/rzepa/blog","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"rzepa","status":"active","subfield":"1606","title":"Henry Rzepa's Blog","updated":1791013525,"use_api":true},"blog_name":"Henry Rzepa's Blog","blog_slug":"rzepa","content_html":"
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The molecule below was characterised in 1996[1] and given the name tris(dithiolene)vanadium (IV). No attempt was made in the original article to give this molecule a [2] Lewis structure using Lewis electron pair bonds. This blog will explore some of the issues that arise when this is attempted.1

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NAMPOG.

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The name given to the molecule by the chemists who made it reflects the ligand used, which we can represent as cis-HS-CH=CH-SH (via its di-sodium salt and reaction with VCl3). Its entry in the Cambridge crystal database is NAMPOG (which carries only the slightest of semantic or structural information). The chemical name however does carry some further information, namely the designation tris implies three fold symmetry (D3h in this case), and hence that all three ligands are in fact identical (structurally).

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A nominal first stab at a Lewis electron pair representation reflecting this symmetry might be as shown above.\u00a0At this point we hit a logical problem with the final component of the assigned name; the formal oxidation state of the metal is designated IV. However, three moles of (-)S-CH=CH-S(-) imply the ligands carry a formal charge of 6-, and that therefore the metal must be 6+, or VI. Six however is not an oxidation state normally exhibited by vanadium. Why did the original discoverers designate it IV? Well, because careful electron counting reveals the system as a whole has 161 electrons, of which 71 are designated as valence electrons, and hence it must have one unpaired valence electron. In the representation above, that electron is shown resident on the V atom with a dot, and the ESR spectrum measured for the molecule turns out to be apparently characteristic of V(IV) systems (they do not mention whether they also compared the spectra with those derived from genuine examples of \u00a0V(II), see below). This implies (as the authors note) that a total of only 4- must be delocalized over the three dithiolene ligands.

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Returning to our electron counting, of the remaining 70 valence electrons, 24 electrons are implicit above as twelve sulfur lone pairs (which are sometimes shown as double dots, but their explicit inclusion here would cause clutter) and so we presume the remaining 46 electrons must be in Lewis-like electron pair bonds. Well, the structure above implies 24 such bonds (the six C-H lines, as well as the \u00a0Hs are also omitted by convention, again to avoid clutter!). We can begin to see why the original article lacks a Lewis structure, since the one above contains too many electrons (48 rather than 46).

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How might one proceed to rescue the situation? Because a great many possible Lewis structures could be drawn, we have to learn a little more about the molecule and seek recourse in the bond lengths measured for the system. The most obvious is the C-C length, which turns out to be 1.36\u00c5, a value significantly longer than expected for a C=C double (i.e. a four electron) bond, but a little shorter than the 3-electron bond found in e.g. benzene.

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A second attempt at a Lewis structure

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The Lewis structure (one of three equivalent ones) now has 5 lines in the C-C region, or ~3.3 electrons per C-C bond averaged over three ligands, which seems to match the length a little better. It also has 25 lines representing nominal electron pairs and ten sulfur lone pairs, a total of 70 electrons. The net effect of this representation is to transfer two electrons from the sulfur lone pairs to the vanadium, and hence to reduce the formal charge at the metal from 6+ to 4+, or to V(IV). This sort of behaviour, where electrons can be borrowed from a ligand and used to reduce (or oxidise) the metal they are coordinated to is called non-innocent behaviour. The dithiolene ligand is notoriously non-innocent. It results in this case in our innocent assumptions that bonds are defined by an integer number of electrons [2,(3),4,(5) or 6 as in Lewis’ original classifications] are no longer adequate, and that non-integer descriptors must also be used.

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There is still one counting rule we have not inspected. To complete its valence shell to reach Kr, V needs 18 valence electrons. The representation above gives it 13. So how about the following, which ends up with a valence shell of 17 electrons for vanadium (and an oxidation state of V(II))?

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Third time lucky?

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This implies that the V-S bonds might be a little shorter than normal. Well in NAMPOG its 2.35\u00c5, perhaps slightly shorter than a typical V-S single bond of ~2.4\u00c5, but in fact we are now down at the noise level, and its clear that we have probably reached (if not exceeded) the limit of semantic interpretation of the Lewis model. In this case, only three (of 100s of possible) Lewis structures have been discussed, and of course they were selected only because we had some experimental information to discriminate between them. And we must be aware that whilst Lewis structures are the simplest way of analysing the electron distribution in a molecule, far more sophisticated analyses are nowadays possible. The real question is which analysis can actually result in a greater insight into the molecule? But the least that can be said about molecule NAMPOG is that it causes one to think about the problems of representing bonding (I will draw the line however at using this example in my university admissions interviews!).

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1 I thank J. P. P. (Jimmy) Stewart for drawing this molecule on my blackboard \u00a0and hence provoking this blog post.

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References

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  1. M. Kondo, S. Minakoshi, K. Iwata, T. Shimizu, H. Matsuzaka, N. Kamigata, and S. Kitagawa, \"Crystal Structure of a Tris(dithiolene) Vanadium(IV) Complex Having Unprecedented <i>D</i>3<i>h</i> Symmetry\", Chemistry Letters, vol. 25, pp. 489-490, 1996. https://doi.org/10.1246/cl.1996.489\n\n
    2. \n
  2. G.N. Lewis, \"THE ATOM AND THE MOLECULE.\", Journal of the American Chemical Society, vol. 38, pp. 762-785, 1916. https://doi.org/10.1021/ja02261a002\n\n
    3. \n
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","doi":"https://doi.org/10.59350/rncje-xe063","guid":"http://www.ch.ic.ac.uk/rzepa/blog/?p=2559","image":"https://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2010/09/V1.jpg","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1285545600,"reference":[{"id":"https://doi.org/10.1246/cl.1996.489","unstructured":"M. Kondo, S. Minakoshi, K. Iwata, T. Shimizu, H. Matsuzaka, N. Kamigata, and S. Kitagawa, \"Crystal Structure of a Tris(dithiolene) Vanadium(IV) Complex Having Unprecedented D3h Symmetry\", Chemistry Letters, vol. 25, pp. 489-490, 1996."},{"id":"https://doi.org/10.1021/ja02261a002","unstructured":"G.N. Lewis, \"THE ATOM AND THE MOLECULE.\", Journal of the American Chemical Society, vol. 38, pp. 762-785, 1916."}],"rid":"knbnq-h9b96","summary":"The molecule below was characterised in 1996 and given the name tris(dithiolene)vanadium (IV). No attempt was made in the original article to give this molecule a Lewis structure using Lewis electron pair bonds.","tags":["Interesting Chemistry","Cambridge","Chemical Name","Historical","Metal"],"title":"(Almost) 100 years of Lewis structures: are they still fit for purpose?","updated_at":1791013424,"url":"https://www.ch.ic.ac.uk/rzepa/blog/?p=2559","version":"v1"}},{"document":{"authors":[{"affiliation":[{"id":"https://ror.org/04aj4c181","name":"Technische Informationsbibliothek (TIB)"}],"contributor_roles":[],"family":"R\u00fccknagel","given":"Jesko","url":"https://orcid.org/0000-0001-8824-8390"}],"blog":{"authors":null,"community_id":"db0d8909-9e37-46d0-b16c-0551f575e86b","created":1749772800,"current_feed_url":null,"description":"Das Blog der TIB \u2013 Leibniz-Informationszentrum Technik und Naturwissenschaften und Universit\u00e4tsbibliothek","doi":"https://doi.org/10.65527/tib","favicon":"https://rogue-scholar.org/api/communities/db0d8909-9e37-46d0-b16c-0551f575e86b/logo","feed_format":"application/atom+xml","feed_url":"https://blog.tib.eu/feed/atom/","filter":null,"generator":"WordPress","home_page_url":"https://blog.tib.eu/","issn":null,"language":"deu","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.65527","relative_url":null,"secure":true,"slug":"tib","status":"active","subfield":"1802","title":"TIB-Blog","updated":1790929692,"use_api":true},"blog_name":"TIB-Blog","blog_slug":"tib","content_html":"

Mit SavE Niedersachsen \u2013 Sicherheit f\u00fcr das audiovisuelle Erbe Niedersachsens ist seit Juli 2026 ein weiteres Projekt an die Landesinitiative Langzeitarchivierung Niedersachsen (LiLA.NDS) angebunden. Das Andockprojekt wird vom Filminstitut Hannover und der Bibliothek der Hochschule Hannover in Zusammenarbeit mit der TIB durchgef\u00fchrt. F\u00fcr die Umsetzung des Projekts ist Johanna Kolmer als wissenschaftliche Projektmitarbeiterin neu zum Team des Filminstituts hinzugekommen. Begleitet wird das Projekt von Prof. Dr. Klaus Gantert, Direktor des Filminstituts, und Thorsten Hoppe M.A., Gesch\u00e4ftsf\u00fchrer des Filminstituts.

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Im Mittelpunkt stehen die digitalen und digitalisierten audiovisuellen Best\u00e4nde des Filminstituts. Anhand dieser Best\u00e4nde werden Strategien und Arbeitsabl\u00e4ufe f\u00fcr ihre digitale Langzeitarchivierung sowie f\u00fcr die nachhaltige Sicherung der zugeh\u00f6rigen Meta- und Forschungsdaten entwickelt und erprobt. Die dabei gewonnenen Erfahrungen sollen zugleich dazu beitragen, \u00fcbertragbare L\u00f6sungsans\u00e4tze f\u00fcr kleinere Kulturerbe-Einrichtungen in Niedersachsen zu entwickeln.

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K\u00f6nnen Sie Ihre Einrichtung und deren Sammlungsschwerpunkte kurz vorstellen?

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Das Filminstitut Hannover ist eine wissenschaftliche Einrichtung der Hochschule Hannover, die sich der Sammlung, Dokumentation, Erschlie\u00dfung und Erforschung von Filmen und filmhistorischen Materialien mit besonderem Bezug zu Hannover und Niedersachsen widmet. Die Best\u00e4nde des Filminstituts Hannover umfassen unter anderem Amateur- und Dokumentarfilme, Produktionsarchive sowie umfangreiche regionalgeschichtliche Film- und Videosammlungen.

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Blick in den Archivbestand des Filminstituts Hannover. Foto: Filminstitut Hannover/Hochschule Hannover
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Viele dieser Aufnahmen stellen einzigartige audiovisuelle Quellen dar. Sie dokumentieren gesellschaftliche Entwicklungen, stadt- und regionalgeschichtliche Prozesse sowie Aspekte des Alltags in Niedersachsen \u00fcber mehrere Jahrzehnte hinweg.

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Gibt es ein digitales Objekt oder eine Sammlung, die Ihnen besonders am Herzen liegt?

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Besonders interessant ist f\u00fcr mich aktuell der Bestand zur EXPO 2000, den das Filminstitut 2025 vom EXPOSEEUM Hannover \u00fcbernommen hat.

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Filmbild, EXPO 2000 Hannover, Bau007. Foto: Filminstitut Hannover/Hochschule Hannover
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Er umfasst mehr als 2.000 Filme und dokumentiert die Weltausstellung aus unterschiedlichen Perspektiven \u2013 von den Vorbereitungen und dem Bau des Ausstellungsgel\u00e4ndes bis hin zu Veranstaltungen und den eigentlichen Ausstellungstagen.

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Der Bestand ist insbesondere deshalb von Interesse, weil die EXPO 2000 ein pr\u00e4gendes Ereignis f\u00fcr Hannover war und das Filmmaterial zugleich zentrale Themen und Diskurse der damaligen Zeit dokumentiert, etwa Zukunftsvorstellungen, Globalisierung, Nachhaltigkeit und technologischen Wandel.

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Die gro\u00dfe Menge und Heterogenit\u00e4t des Materials macht den Bestand zudem f\u00fcr Fragestellungen der digitalen Langzeitarchivierung besonders relevant.

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Was motiviert Sie, Ihre digitalen Best\u00e4nde zu archivieren? Gab es einen Ausl\u00f6ser, der den Ansto\u00df gegeben hat, sich mit der digitalen Langzeitarchivierung auseinanderzusetzen?

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Das Filminstitut digitalisiert seine historischen Filmbest\u00e4nde bereits seit vielen Jahren. Im Zuge dieser kontinuierlichen Digitalisierung ist ein umfangreicher digitaler Bestand entstanden. Gleichzeitig zeigt sich, dass die Digitalisierung allein noch keine dauerhafte Sicherung und langfristige Nutzbarkeit der Materialien gew\u00e4hrleistet.

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Digitale Dateien unterliegen eigenen Risiken: Speichermedien k\u00f6nnen ausfallen, Dateien k\u00f6nnen besch\u00e4digt werden, Dateiformate langfristig obsolet werden und relevante Kontextinformationen verloren gehen. Gerade bei umfangreichen audiovisuellen Best\u00e4nden sind daher verl\u00e4ssliche und nachvollziehbar dokumentierte Strukturen erforderlich, um die Integrit\u00e4t, Interpretierbarkeit und Nutzbarkeit der Daten langfristig sicherzustellen. Diese Herausforderung bildet einen wesentlichen Ausgangspunkt f\u00fcr SavE Niedersachsen.

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Welche Unterst\u00fctzung ist f\u00fcr Sie im Projekt besonders wertvoll?

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Besonders wertvoll ist f\u00fcr uns der fachliche Austausch mit der TIB und den weiteren Einrichtungen innerhalb von LiLA.NDS. Die digitale Langzeitarchivierung umfasst zahlreiche technische, organisatorische und konzeptionelle Fragestellungen, bei deren Bearbeitung wir von bereits vorhandenen Erfahrungen und entsprechender Expertise profitieren k\u00f6nnen.

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Gleichzeitig bietet die Zusammenarbeit die M\u00f6glichkeit, die spezifischen Anforderungen audiovisueller Best\u00e4nde in den gemeinsamen Austausch einzubringen. Besonders wichtig ist dabei die gemeinsame Entwicklung und Erprobung praktikabler und m\u00f6glichst \u00fcbertragbarer L\u00f6sungsans\u00e4tze. Der Wissenstransfer innerhalb des Netzwerks erm\u00f6glicht es, unterschiedliche Perspektiven zusammenzuf\u00fchren und Herausforderungen der digitalen Langzeitarchivierung gemeinschaftlich zu bearbeiten.

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Blogreihe \"LiLA.NDS\"

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Im Rahmen einer begleitenden Blogreihe werden wir regelm\u00e4\u00dfig \u00fcber den Projektfortschritt Landesinitiative Langzeitarchivierung Niedersachsen (kurz LiLA) berichten. So erhalten Interessierte au\u00dferhalb des Projektkonsortiums Einblicke in die Arbeit von LiLA. In den kommenden Beitr\u00e4gen stellen sich die beteiligten Einrichtungen vor, berichten \u00fcber ihre zu archivierenden Best\u00e4nde und erl\u00e4utern, warum die digitale Langzeitarchivierung f\u00fcr sie von besonderer Bedeutung ist. Damit ist die Blogreihe eine wichtige S\u00e4ule in der geplanten Wissensbasis, die es dem Projekt erm\u00f6glicht, Best Practices vorzustellen und Einblicke in die Umsetzungsphase zu geben.
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","doi":"https://doi.org/10.65527/qt0rp-2fr16","guid":"https://blog.tib.eu/?p=33814","image":"https://blog.tib.eu/wp-content/uploads/2026/09/Filmbild-EXPO-2000-Hannover-Bau007.-\u00a9-Filminstitut-Hannover-Hochschule-Hannover.jpg","language":"de","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790899200,"rid":"dhf3n-2w009","summary":"Mit SavE Niedersachsen \u2013 Sicherheit f\u00fcr das audiovisuelle Erbe Niedersachsens ist seit Juli 2026 ein weiteres Projekt an die Landesinitiative Langzeitarchivierung Niedersachsen (LiLA.NDS) angebunden. Das Andockprojekt wird vom Filminstitut Hannover und der Bibliothek der Hochschule Hannover in Zusammenarbeit mit der TIB durchgef\u00fchrt.","tags":["FORSCHUNG & PROJEKTE","LiLA.NDS","Lizenz:CC-BY-4.0-INT","Digitale Langzeitarchivierung","Landesinitiative Langzeitarchivierung Niedersachsen"],"title":"Digitales Kulturerbe bewahren \u2013 SavE Niedersachsen sichert audiovisuelle Best\u00e4nde des Filminstituts Hannover","updated_at":1791012614,"url":"https://blog.tib.eu/2026/10/02/digitales-kulturerbe-bewahren-save-niedersachsen-sichert-audiovisuelle-bestaende-des-filminstituts-hannover/","version":"v1"}},{"document":{"authors":[{"affiliation":[{"name":"Sky Publishing Corp, Sky & Telescope"}],"contributor_roles":[],"family":"Wedel","given":"Mathew","url":"https://orcid.org/0000-0001-6082-3103"}],"blog":{"authors":[{"name":"Mike Taylor"}],"community_id":"0e13541f-417e-46c0-a859-65927249df72","created":1675209600,"current_feed_url":null,"description":"SV-POW! ... All sauropod vertebrae, except when we're talking about Open Access. ISSN 3033-3695","doi":"https://doi.org/10.59350/svpow","favicon":"https://rogue-scholar.org/api/communities/0e13541f-417e-46c0-a859-65927249df72/logo","feed_format":"application/atom+xml","feed_url":"https://svpow.com/feed/atom/","filter":null,"generator":"WordPress.com","home_page_url":"https://svpow.com","issn":"3033-3695","language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"svpow","status":"active","subfield":"1911","title":"Sauropod Vertebra Picture of the Week","updated":1790926474,"use_api":true},"blog_name":"Sauropod Vertebra Picture of the Week","blog_slug":"svpow","content_html":"

If you travel in the same circles I do, you probably know that my friend and colleague Mark Witton is working on a speculative biology book, Dinosaurs Evolved, that takes a fresh look at what life on Earth might be like now had the asteroid missed and the K-Pg extinction never happened. As a lifelong spec-bio fan, I’m stoked for that project. Speculative sauropods have given me a lot to think about, especially in the past few years, so I thought it would be fun to revisit some in this post. Maybe all? There aren’t a ton of examples. If you know of any I missed here, sing out in the comments. (I’m not including any from the Speculative Dinosaur Project out of lack of familiarity — the project was basically dead by the time I would have started following it — and I’m not sure any are currently accessible anyway.)

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Rather than proceeding chronologically, I’m going to start with my favorites and proceed in the direction of the most-loathed, for reasons that will become apparent later on. Back in 2010, Memo K\u00f6semen kindly let us — Mike, Darren, and me — debut his Brontosapiens here on SV-POW!, and give our thoughts on it. I’m not going to say much about this critter in this post, mostly because I think our ideas from 16 years ago hold up pretty well, and you can just go read the original post if you’re curious.

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Pp. 42-43 in The New Dinosaurs. (c) Dougal Dixon and Breakdown Press 2025.

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Of course the OG speculative sauropods are the ones dreamt up by Dougal Dixon for The New Dinosaurs (1988), the recent reprint of which I reviewed here. In addition to the ones shown above, there are a couple more in the book: a dwarf island sauropod, which we now know actually happened more than once, and the Rajaphant, which is basically an unremarkable large titanosaur. Of the ones in the above spread, the Lumber has a trunk and is actually built for it, unlike any real-world sauropods discovered so far, and the Turtosaur takes titanosaur osteoderms to their logical conclusion. I like ’em both. The box on the far left shows the skeleton of a group of slender-bodied running sauropods that flourished only briefly during Dixon’s alternate Cenozoic.

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I’m not going to say much about the brontosaurs in Peter Jackson’s King Kong (2005), because they’re not really attempts at spec bio, but rather deliberately old-fashioned Charles R. Knight/Rudolph Zallinger-esque productions realized in CG. I’ll say of the movie that it has a lot of dinosaurs but not particularly interesting ones; if you thought that the Jurassic Park/World movies were too realistic and you’d prefer your dinosaurs to look like cliches from decades past and act like voracious monsters, King Kong has you covered. That said, as monster fights go, King Kong vs. three V. rexes is a banger.

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Much more interesting from a spec bio perspective is a book that accompanied the movie, The World of Kong: A Natural History of Skull Island. It explains the fictional evolutionary backstory of the Skull Island critters from the movie, both the ones that made it to the screen, and many others that did not. Among those never realized on screen are two sauropods. The first, shown above, is Asperdorsus (“rough back”), which has spines on its back and hanging from its neck. This is pretty much just a spiny Diplodocus and it wouldn’t surprise me if someone dug one of these up in Montana while I was writing this post.

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Then there’s this thing, Diablosaurus, which I have an almost visceral dislike of, for many reasons. First off, it’s boring. It’s just a dinosaur squeezed into the shape of a rhinoceros. In a world with the full-tilt wackiness of actual ceratopsians (f’rinstance) — of which there were also fictional examples on Skull Island! — a rhino-alike with horns but no frill is both uninspired and unexciting. Also, hello, Iguanodon from the 1830s is calling.

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But it gets worse. Although the skeletal diagram shows that this dumb thing was clearly an ornithischian, or at least had an ornithischian pelvis, the text says that it’s an aberrant sauropod. Er, wut? I guess some Camarasaurus finally got drunk enough to evolve into an ornithischian and then into a mammal-shaped ornithischian. Of course it would.

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I should give some credit to Diablosaurus, though, because it forced me to think about why I hated it so much. That got me thinking about what actual sauropods did, evolutionarily (be large-bodied, long-necked and long-tailed, graviportal, non-oral-processing oviparous quadrupedal herbivores), and what they did not do (er, pretty much everything else, including being Diablosaurus-like).

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My “nontosaurs”: the gazelleopod, antlertitan, and poseidonposeidon.

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And that led to my “Sauropod Heresies” mini-paper and talk for the Tate 2024 conference (link), which I tuned up with another year’s worth of thoughts for DinoCon 2025. The image above is a doodle I did for those talks, illustrating some of the paths not taken in sauropod evolution. If real sauropods were brontosaurs, I call the ‘forbidden’ experiments, including Diablosaurus, the nontosaurs.

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To bring this full circle, Mark Witton has been kind enough to share some behind-the-scenes thinking for Dinosaurs Evolved, and he’s thought of some ways out of what we might call “brontosaur lock-in” that hadn’t occurred to me, but which I think are eminently plausible. One of them is the subject of a recent post on his Patreon. I’ll say no more for now, but let’s circle back after the book is out, to revisit both speculative sauropods and the real and imagined limits on the sauropod body plan.

","doi":"https://doi.org/10.59350/vweh2-9sk08","guid":"https://svpow.com/?p=25978","image":"https://svpow.wordpress.com/wp-content/uploads/2010/06/nemos-brontosapiens.png?w=480","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790899200,"rid":"34kn1-jmv09","summary":"If you travel in the same circles I do, you probably know that my friend and colleague Mark Witton is working on a speculative biology book, Dinosaurs Evolved, that takes a fresh look at what life on Earth might be like now had the asteroid missed and the K-Pg extinction never happened.","tags":["Brontosapiens","Cenozoic Dinosaurs","Dougal Dixon","Speculation","Speculative Biology"],"title":"Speculative sauropods","updated_at":1791012611,"url":"https://svpow.com/2026/10/02/speculative-sauropods/","version":"v1"}},{"document":{"authors":[{"affiliation":[{"name":"Freie Universit\u00e4t Berlin, Open Research Office Berlin"}],"contributor_roles":[],"family":"Duine","given":"Maaike","url":"https://orcid.org/0000-0003-3412-7192"}],"blog":{"authors":null,"community_id":"52aefd81-f405-4349-b080-754395a5d8b2","created":1694476800,"current_feed_url":null,"description":null,"doi":"https://doi.org/10.59350/oaberlin","favicon":"https://rogue-scholar.org/api/communities/52aefd81-f405-4349-b080-754395a5d8b2/logo","feed_format":"application/atom+xml","feed_url":"https://blogs.fu-berlin.de/open-research-berlin/feed/atom/","filter":null,"generator":"WordPress","home_page_url":"https://blogs.fu-berlin.de/open-research-berlin","issn":null,"language":"deu","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"oaberlin","status":"active","subfield":"1802","title":"Open Research Blog Berlin","updated":1790941290,"use_api":true},"blog_name":"Open Research Blog Berlin","blog_slug":"oaberlin","content_html":"

Orte und Tools f\u00fcr digitales, nicht-kommerzielles Publizieren

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Faires, wissenschaftsgeleitetes Open-Access-Publizieren gewinnt zunehmend an Bedeutung, nicht zuletzt durch die Priorisierungsagenda der BUA-Einrichtungen zur Umsetzung des Open-Science-Leitbilds und das Positionspapier zu Open Research der Berliner Landesinitiative. Doch welche Alternativen zu etablierten, oft kommerziellen Publikationswegen gibt es eigentlich, und wie funktionieren sie?

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In diesem einst\u00fcndigen Lunch Meeting stellen wir Ihnen ausgew\u00e4hlte Orte und Tools f\u00fcr digitales Publizieren vor, von fachspezifischen Verlagen wie SciPost oder Open Library of Humanities bis hin zu neuen Publishing-Tools wie Octopus und ResearchEquals. Ein Praxisbericht von Forschenden erg\u00e4nzt die Vorstellung der Publishing-Tools. Dar\u00fcber hinaus geben wir Einblick in die Angebote von Berlin Universities Publishing. Im Anschluss bleibt ausreichend Zeit f\u00fcr Fragen und Diskussion.

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Das Meeting findet im Rahmen der internationalen Open Access Week statt und richtet sich an alle Forschenden, die mehr \u00fcber faire und offene Publikationsm\u00f6glichkeiten erfahren m\u00f6chten. Das Thema der diesj\u00e4hrigen Open Access Week lautet \"The Cost of Knowledge\": Entsprechend nehmen wir das Motto zum Anlass, um Alternativen zu kommerziell ausgerichteten Publikationsm\u00f6glichkeiten vorzustellen.

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Offen und fair Publizieren: Orte und Tools f\u00fcr digitales, nicht-kommerzielles Publizieren\n-Wann: Montag, 19.10.2026, 13:00-14:00 Uhr\n-Wo: Online\n-Registrierung: Anmeldung per Webex
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Organisiert von:

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","doi":"https://doi.org/10.59350/xcjqw-q0t82","guid":"https://blogs.fu-berlin.de/open-research-berlin/?p=4343","language":"de","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1789603200,"rid":"99595-v5p57","summary":"Orte und Tools f\u00fcr digitales, nicht-kommerzielles Publizieren Faires, wissenschaftsgeleitetes Open-Access-Publizieren gewinnt zunehmend an Bedeutung, nicht zuletzt durch die Priorisierungsagenda der BUA-Einrichtungen zur Umsetzung des Open-Science-Leitbilds und das Positionspapier zu Open Research der Berliner Landesinitiative.","tags":["Allgemein","Aktuelles","Berlin","Bibliotheken","Open Access"],"title":"Online Lunch Meeting: Offen und fair Publizieren","updated_at":1791012607,"url":"https://blogs.fu-berlin.de/open-research-berlin/2026/09/17/online-lunch-meeting-offen-und-fair-publizieren/","version":"v1"}},{"document":{"authors":[{"contributor_roles":[],"family":"Priego","given":"Ernesto"}],"blog":{"authors":[{"name":"Ernesto Priego"}],"community_id":"ae617b4e-ce60-495f-a839-e05f4c0da6b5","created":1698796800,"current_feed_url":null,"description":"Ernesto Priego's blog. A personal repository of stuff.","doi":"https://doi.org/10.59350/ernestopriego","favicon":"https://rogue-scholar.org/api/communities/ae617b4e-ce60-495f-a839-e05f4c0da6b5/logo","feed_format":"application/atom+xml","feed_url":"https://ernestopriego.com/feed/atom/","filter":null,"generator":"WordPress.com","home_page_url":"https://ernestopriego.com","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"ernestopriego","status":"active","subfield":"1213","title":"Everything is Connected","updated":1790950930,"use_api":true},"blog_name":"Everything is Connected","blog_slug":"ernestopriego","content_html":"
\"Ernesto
Yours Truly (left) with graphic novelists Francisco de la Mora, Gemma Plum and Zara Slattery
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Panels & Perspectives: Panel on Disability and Neurodiversity in Comics took place at AG01, Thursday, October 1st 2026 in the College Building, City St George’s, University of London. The panel successfully explored how graphic novels can challenge stereotypes, create connections and invite readers to the world from different perspectives. The session was well attended with the room at full capacity.

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Calling upon the powerful true stories behind their work, graphic novelists Francisco de la Mora, Gemma Plum and Zara Slattery examined how comics can make visible experiences that are often overlooked, opening up conversations about disability, neurodiversity, care and belonging.

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The event coincided with the official UK release of Gemma Plum's The Great Marc Evers. The True Story of a Champion Against All Odds (Selfmadehero 2026), which tells in comics form 'the inspiring life story of one of the greatest Paralympic swimming champions, and his family that stopped focusing on a \"no\" to find a \"yes\".'

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Each member of the panel spoke of what had first drawn them to graphic storytelling, and made a short presentation about each of the books featured in the event, with themes related to disability and neurodiversity:

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The Most Amazing Saturday Morning Rubbish Club, by Francisco de la Mora and Bill Tuckey (Selfmadehero, 2025).

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The Great Marc Evers: The True Story of a Champion Against All Odds, by Gemma Plum, Ivo van Woerden and Marloes Dekkers (Selfmadehero 2026), and

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Coma, by Zara Slattery (Myriad Editions, 2021).

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Internal and external participants, including Human Computer Interaction Design MSc students from the 2025-26 and 2026-27 cohort, who engaged in the Q&A and chatted with the authors, bought their books and got them signed after the panel over refreshments.

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\"Gemma
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This event also provided an opportunity to talk about Ernesto's Parables of Care project creating comics about dementia care, and copies were distributed freely with participants who had not heard of the project before.

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\"Copies
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\"An
One member of the audience even did some sketch-noting during the panel in comics form!
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This activity also informally launched my Sabbatical research leave!

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This event was organised in collaboration with comics publisher Selfmadehero.

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Participants consented to being photographed for documentation purposes. Thank you to everyone who attended and participated; it was a joyous occasion.

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","doi":"https://doi.org/10.59350/ymbc3-w2j61","guid":"https://ernestopriego.com/?p=11990","image":"https://i0.wp.com/ernestopriego.com/wp-content/uploads/2026/10/image-1.jpeg?fit=2048%2C1536&ssl=1","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790899200,"rid":"pw0n8-ynh06","summary":" Panels & Perspectives: Panel on Disability and Neurodiversity in Comics took place at AG01, Thursday, October 1 st 2026 in the College Building, City St George's, University of London. The panel successfully explored how graphic novels can challenge stereotypes, create connections and invite readers to the world from different perspectives. The session was well attended with the room at full capacity.","tags":["Comics","Events"],"title":"Panels and Perspectives: Exploring Disability and Neurodiversity Through Comics","updated_at":1791012607,"url":"https://ernestopriego.com/2026/10/02/panels-and-perspectives-exploring-disability-and-neurodiversity-through-comics/","version":"v1"}}],"items":[{"authors":[{"affiliation":[{"name":"University of Wroc\u0142aw, Chemistry"}],"contributor_roles":[],"family":"Janeta","given":"Mateusz","url":"https://orcid.org/0000-0003-2197-7913"}],"blog":{"authors":null,"community_id":"c21eed24-c860-43d0-997c-0bc782922544","created":1788652800,"current_feed_url":null,"description":null,"doi":"https://doi.org/10.59350/silsesquioxane","favicon":"https://rogue-scholar.org/api/communities/c21eed24-c860-43d0-997c-0bc782922544/logo","feed_format":"application/atom+xml","feed_url":"https://silsesquioxane.blogspot.com/feeds/posts/default","filter":null,"generator":"Blogger","home_page_url":"https://silsesquioxane.blogspot.com/","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"silsesquioxane","status":"active","subfield":"1604","title":"Polyhedral Oligomeric Silsesquioxane (POSS) Chemistry","updated":1791045034,"use_api":true},"blog_name":"Polyhedral Oligomeric Silsesquioxane (POSS) Chemistry","blog_slug":"silsesquioxane","content_html":"

Epoxy nanocomposite vitrimers containing polyhedral oligomeric silsesquioxane (POSS) were reported by Hongkun Yang, Changfei He, Thomas P. Russell, and Dong Wang in Giant in 2020. Studies devoted specifically to POSS in vitrimer networks remain scarce, and this one still carries the subject almost on its own. Glycidyl POSS was incorporated as a nanoscale filler into a transesterification-based epoxy, raising tensile strength and strain at break simultaneously while shifting the topology-freezing transition upward by more than 36 \u00b0C. A handful of related reports place silsesquioxane particles in other dynamic matrices, among them the bio-based polymethacrylate vitrimer nanocomposites of Hajiali, Tajbakhsh, and Mari\u0107, and in every case the cage serves as reinforcing filler.

Key findings at a glance
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Over the same period the silicon\u2013oxygen bond has become one of the most productive dynamic covalent motifs in vitrimer design, through TBD-catalyzed siloxane exchange from the Du Prez group and through direct silyl ether metathesis discovered in the Guan laboratory. The two routes act on different bonds, Si\u2013O\u2013Si in the first case and Si\u2013O\u2013C in the second. The T8 silsesquioxane cage is built from twelve Si\u2013O\u2013Si bridges, structurally the same linkage that the Du Prez system exchanges in under six seconds, yet the question of whether those bridges can act as the dynamic site, rather than as inert structural scaffolding, appears not to have been put. What follows sets out what is established across five studies and identifies the control experiment that would settle the question.

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Associative vs Dissociative Covalent Adaptable Networks: What Defines a Vitrimer

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Covalent adaptable networks divide into two families, and the distinction governs everything that follows. In a dissociative mechanism the crosslink breaks before a new bond forms, so the crosslink density falls transiently, the viscosity drops sharply, and at sufficiently high temperature the network can depolymerize outright. The reversible Diels\u2013Alder reaction is the canonical example. In an associative mechanism the incoming partner binds before the original bond is cleaved, so the number of crosslinks remains constant across the entire temperature range. The material rearranges its topology without ever losing network integrity, and it was this class that Ludwik Leibler named vitrimers in 2011, in the work by Damien Montarnal and co-workers that established silica-like malleability in a permanent organic network.

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\"POSS
Fig. 1. Two families of covalent adaptable networks. In the dissociative mechanism (a) the crosslink is cleaved first, which lowers the crosslink density transiently and, in the limit, costs the network its integrity. In the associative mechanism (b) the exchange partner adds before the original bond breaks, by way of the transition state marked with a dotted circle, so the number of junctions stays constant. Vitrimers belong exclusively to the second group. Redrawn from: Denissen, W.; Winne, J. M.; Du Prez, F. E. Chem. Sci. 2016, 7, 30. DOI: 10.1039/C5SC02223A, Fig. 1.
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Arrhenius Flow and the Topology-Freezing Transition (Tv) of Vitrimers

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The rheological consequence of associative exchange is best seen on an Angell fragility plot. Thermoplastics possess a narrow glass transition across which the viscosity collapses by orders of magnitude within a few tens of degrees, which in practice means a narrow processing window and a requirement for close temperature control. Vitrimers behave differently: their viscosity follows an Arrhenius law over a very wide temperature range, in the manner of silica rather than polystyrene. In rheological terminology they are strong liquids, and the practical consequence is a material that can be shaped with the tolerance of a silicate glass rather than the precision demanded by a thermoplastic melt.

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\"Angell
Fig. 2. Angell fragility plot. Thermoplastics (PS, PVC) show the steep, almost vertical viscosity collapse characteristic of fragile liquids. The epoxy\u2013POSS vitrimers fall along a straight line, as silica does, indicating Arrhenius flow and a broad processing window. Their fragility indices are 13 for the unfilled network and 16 at 10 wt% POSS, both below the value of roughly 20 for SiO\u2082. Vitrimer points were calculated from the Ea and Tv values in Yang, H.; He, C.; Russell, T. P.; Wang, D. Giant 2020, 4, 100035, Table 2. DOI: 10.1016/j.giant.2020.100035; reference curves were generated with the MYEGA model of Mauro, J. C.; Yue, Y.; Ellison, A. J.; Gupta, P. K.; Allan, D. C. Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 19780. DOI: 10.1073/pnas.0911705106.
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The temperature at which the viscosity passes 10\u00b9\u00b2 Pa\u00b7s defines the topology-freezing transition, Tv. Above it the network is a viscoelastic liquid with a fixed junction count; below it the material is an elastomer or a glass. Together with Tg this provides two independent handles on the mechanical response, and much of the interest in filled vitrimers comes from the possibility of moving one without moving the other.

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Synthesis of Functionalized POSS Cages: Condensation, Corner Capping, Hydrosilylation

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Any discussion of POSS in dynamic networks has to begin with how the cages are made, because the available substitution patterns determine what network architectures are reachable. The cubic T8 framework, Si\u2088O\u2081\u2082R\u2088, forms by hydrolytic condensation of a trifunctional silane RSiX\u2083 where X is chloride or alkoxide. The reaction is run in dilute solution, often for days, and for many R groups the closed cubic cage is the thermodynamic sink, so the process is self-correcting if given enough time. Yields are strongly substituent-dependent, and the same conditions that deliver a clean octamer for one R group can give a mixture of T8, T10, and T12 cages for another. Octa(3-aminopropyl)silsesquioxane, the building block behind much of the functional POSS work from the University of Wroc\u0142aw, is obtained this way from 3-aminopropyltriethoxysilane and then elaborated by amide coupling at the eight peripheral amines.

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Two further routes matter for network chemistry. Corner capping starts from an incompletely condensed trisilanol, R\u2087Si\u2087O\u2089(OH)\u2083, and closes the eighth vertex with a different RSiCl\u2083, which gives a cage bearing seven of one substituent and one of another. This is the standard way to make a monofunctional POSS for pendant attachment. Platinum-catalyzed hydrosilylation of octahydridosilsesquioxane, Si\u2088O\u2081\u2082H\u2088, with a terminal alkene gives octa-substituted cages directly and tolerates a wide range of functionality, which is how the glycidyl cages used in vitrimer work are most conveniently accessed. Octaglycidyl cages are most reliably prepared by hydrosilylation of Si\u2088O\u2081\u2082H\u2088 with allyl glycidyl ether, since the direct hydrolytic condensation of (3-glycidoxypropyl)trimethoxysilane is complicated by the sensitivity of the oxirane ring to the acid or base used to promote condensation. Commercial glycidyl POSS is supplied in some grades as a cage mixture rather than a pure octamer, so the stoichiometry is worth checking in any given batch. Yang and co-workers used material from Hybrid Plastics and report a molar mass of 1337.88 g/mol with an epoxy equivalent weight of 167. Those values match the calculated mass of Si\u2088O\u2081\u2082(C\u2086H\u2081\u2081O\u2082)\u2088 at 1337.9 g/mol and one eighth of it at 167.2, so their material corresponds to full octa-substitution of a T8 cage.

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The same Karstedt hydrosilylation chemistry appears again in the silicone vitrimer discussed later in this post, where allyl glycidyl ether is added across the two Si\u2013H bonds of 1,1,3,3-tetramethyldisiloxane to give a difunctional siloxane epoxide. What matters for the argument developed here is that none of this requires new synthetic methodology. Every cage and every linker involved is either commercial or accessible in one step from commercial material, which means the experiment proposed at the end of this post can be attempted immediately.

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Epoxy\u2013POSS Nanocomposite Vitrimers by Hydroxyl\u2013Ester Transesterification

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The only dedicated POSS vitrimer study uses a formulation assembled entirely from catalogue reagents. Yang and co-workers combined diglycidyl ether of bisphenol A (DER 332), dodecanedioic acid as the hardener, and glycidyl POSS, with 1,5,7-triazabicyclo[4.4.0]dec-5-ene at 2.5 mol% relative to carboxyl groups as the transesterification catalyst. The components were heated to 160 \u00b0C with stirring, the catalyst was added, and the homogeneous melt was poured into preheated PTFE molds and cured for six hours at 160 \u00b0C. POSS was introduced at 2, 5, 8, and 10 wt%, with the DGEBA fraction adjusted each time to hold the epoxy to carboxyl stoichiometry at unity. The low viscosity of glycidyl POSS and its miscibility with DGEBA make this a genuinely homogeneous system rather than a dispersion, which matters because aggregation is the usual failure mode for silica-type fillers in epoxy networks.

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The exchange chemistry is hydroxyl\u2013ester transesterification. Secondary hydroxyl groups generated by epoxide ring opening attack ester linkages elsewhere in the network, transferring a junction without changing the total number of junctions. Infrared spectroscopy confirmed essentially complete conversion: the epoxide bands of DGEBA at 915 cm\u207b\u00b9 and of POSS at 909 and 1199 cm\u207b\u00b9 disappeared, while the ester carbonyl appeared at 1737 cm\u207b\u00b9. Swelling in chlorobenzene for 72 hours left every sample insoluble, with gel fractions rising from 97.12% for the unfilled network to 98.06% at 10 wt% POSS and crosslink densities increasing from 7.04 to 10.6 \u00d7 10\u207b\u2074 mol cm\u207b\u00b3.

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\"Synthesis
Fig. 3. Construction of the epoxy\u2013POSS nanocomposite vitrimer. The upper panel shows the three components: DGEBA (blue), dodecanedioic acid (green), and the octafunctional glycidyl POSS cage, cured with TBD at 2.5 mol% relative to carboxyl groups. The lower panel shows the resulting network, in which the T8 cage serves as an eight-arm junction and the orange markers indicate ester linkages formed on epoxide ring opening. The two insets show both states of the exchange: an ester bond with its neighbouring free hydroxyl, and the product after transesterification. That hydroxyl group is what carries the network dynamics. Redrawn from: Yang, H.; He, C.; Russell, T. P.; Wang, D. Giant 2020, 4, 100035. DOI: 10.1016/j.giant.2020.100035, Scheme 1.
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The mechanical results are unusual in that two properties normally traded against one another both improve. At 10 wt% POSS the ultimate tensile strength rises from 21.9 \u00b1 0.5 to 35.8 \u00b1 0.5 MPa, an increase of 63.5%, while the strain at break rises from 190 \u00b1 15% to 334 \u00b1 20%, an increase of 75.8%. Reinforcement almost always costs ductility, so simultaneous gains call for an explanation, and the authors attribute it to two distinct roles played by the cage. The eight glycidyl arms raise the crosslink density, which accounts for the strength, while the molecularly dispersed, nanoporous cage absorbs deformation energy, which accounts for the toughness.

\n
\"Tensile
Fig. 4. Strength and ductility increase together. Ultimate tensile strength and strain at break plotted against POSS loading. Both rise monotonically, which is atypical of filled systems, where reinforcement is normally paid for in ductility. Data from Yang, H.; He, C.; Russell, T. P.; Wang, D. Giant 2020, 4, 100035, Table 2. DOI: 10.1016/j.giant.2020.100035.
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Two properties move in the opposite direction. The Young's modulus falls from 799 \u00b1 11 to 632 \u00b1 23 MPa, and the glass transition temperature decreases from 34.8 to 27.1 \u00b0C by DMA and from 27.1 to 25.2 \u00b0C by DSC, with the 8 wt% sample departing from the trend in the DMA series and the 10 wt% sample departing from it in the DSC series. A decrease in Tg alongside an increase in crosslink density looks contradictory, and it is one of the more interesting details in the paper. The branched glycidyl POSS modifies the network topology and introduces a side-chain effect that outweighs the stiffening contributed by the additional junctions, an outcome previously documented for monofunctional POSS in epoxy networks by Abad and co-workers.

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POSS Vitrimer Relaxation Kinetics: Decoupling Creep Resistance from Processability

\n

The title of the Yang paper promises efficient relaxation, and the data say something more subtle. Stress relaxation at 160 \u00b0C slows from 7.4 minutes in the unfilled vitrimer to 27.0 minutes at 10 wt% POSS, a factor of 3.6. The activation energy for exchange rises from 82.26 \u00b1 2.05 to 107.90 \u00b1 3.48 kJ mol\u207b\u00b9, and the topology-freezing temperature climbs from 49.1 to 85.5 \u00b0C. Every one of these numbers points the same way: POSS slows the network dynamics.

\n

Read as a deficiency this would be a poor result, but that reading misses what the numbers describe. The network still relaxes completely at 1% strain, so it remains fully reprocessable, and the authors demonstrate this by cutting a specimen into pieces and remolding it with no loss of ultimate tensile strength across cycles. What changes is the temperature at which flow begins. A higher Tv means better creep resistance at service temperature, and a rubbery modulus at 150 \u00b0C that doubles from 1.77 to 3.75 MPa means better dimensional stability. The cage therefore separates two properties that are coupled in a conventional vitrimer: strength at the temperature of use and flow at the temperature of processing. That is precisely the function expected of a well-designed network junction.

\n
\"Relaxation
Fig. 5. Three independent measures of network dynamics agree. Relaxation time at 160 \u00b0C (7.4 to 27.0 min), activation energy for exchange (82.3 to 107.9 kJ mol\u207b\u00b9), and topology-freezing temperature (49.1 to 85.5 \u00b0C) all rise together on going from 0 to 10 wt% POSS. The network still relaxes completely; what changes is the rate, not the capacity. Data from Yang, H.; He, C.; Russell, T. P.; Wang, D. Giant 2020, 4, 100035, Table 2. DOI: 10.1016/j.giant.2020.100035.
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TBD-Catalyzed Siloxane Exchange in Vitrimers and the Role of the N\u2013H Proton

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While POSS has barely entered vitrimer chemistry, the silicon\u2013oxygen bond has entered it along two independent routes. The first was opened by Peng Zheng and Thomas McCarthy in 2012, who showed that siloxane equilibration provides a simple and robust self-healing mechanism in polysiloxanes. The limitation of that chemistry was speed: every material built on it relaxed over at least several hundred seconds, which places it outside any realistic industrial processing window.

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The breakthrough came from the Du Prez group at Ghent University. Tapas Debsharma and co-workers reported in JACS in 2022 a siloxane exchange pathway catalyzed by TBD in the presence of hydroxyl groups, mechanistically a proton shuttling process analogous to the TBD-catalyzed polymerization of cyclic siloxanes described by Fuchise, Shimada, and co-workers. They established the pathway with a model study in which 1,3-divinyltetramethyldisiloxane and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane were heated together at 120 \u00b0C for 16 hours under four sets of conditions. Silicon-29 NMR showed new resonances at 4.1 and 8.4 ppm, adjacent to the starting materials at 7.5 and 3.2 ppm, when both TBD and pentanol were present. Neither alcohol alone nor a metathesis-type pathway produced any exchange. TBD without added pentanol gave the same resonances only faintly, which the authors attribute to residual moisture or to silanol groups on the glass of the reaction vial, and which supports rather than weakens the role assigned to the hydroxyl.

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The mechanistic evidence rests not on a single control but on a screen of seven catalysts, and that is the most persuasive part of the work. The ionic bases all function, though not by a single route: tert-butoxide most likely deprotonates the secondary alcohol formed in the epoxy-amine reaction and starts the exchange as an alkoxide rather than as a siloxide, while trimethylsilanolate and tetramethylammonium siloxanolate supply siloxide directly. Loadings differ too, since tert-butoxide is inactive at 3 mol% and works at 6, and tetramethylammonium siloxanolate decomposes above 150 \u00b0C and has to be processed at 180 \u00b0C rather than 220 \u00b0C. Among the neutral organic bases only TBD works; MeTBD, DBU, and DMAP give no measurable exchange after an hour at 220 \u00b0C. The decisive comparison is the first pair. TBD and MeTBD have nearly identical basicity and differ only in that the N\u2013H group of MeTBD is capped with a methyl, yet capping that single proton switches the catalysis off completely. The failure of DBU and DMAP shows in addition that strong amidine or pyridine basicity is not on its own sufficient. Taken together, the screen indicates that the N\u2013H proton participates directly in the catalytic cycle rather than acting only through basicity.

\n
\"Catalytic
Fig. 6a. Proposed pathway for TBD-catalyzed siloxane exchange in the presence of hydroxyl groups. TBD acts as a proton shuttle, with the N\u2013H group participating directly in the cycle. The lack of catalytic activity shown by MeTBD, which has comparable basicity, supports this assignment. Redrawn from: Debsharma, T.; Amfilochiou, V.; Wr\u00f3blewska, A. A.; De Baere, I.; Van Paepegem, W.; Du Prez, F. E. J. Am. Chem. Soc. 2022, 144, 12280. DOI: 10.1021/jacs.2c03518, Scheme 2.
\n
\"Catalyst
Fig. 6b. The catalyst screen. The ionic bases tBuOK, SiMe\u2083OK, and TMAS all promote exchange by generating siloxide. Among the neutral organic bases only TBD is active; MeTBD, DBU, and DMAP give no measurable exchange. The comparison between TBD and MeTBD is decisive, since the two differ only by a methyl group on nitrogen and have essentially the same basicity. Redrawn from: Debsharma, T.; Amfilochiou, V.; Wr\u00f3blewska, A. A.; De Baere, I.; Van Paepegem, W.; Du Prez, F. E. J. Am. Chem. Soc. 2022, 144, 12280. DOI: 10.1021/jacs.2c03518, Scheme 3.
\n

The resulting material is prepared by curing DGEBA with the siloxane diamine at 120 \u00b0C in the presence of 10 mol% TBD relative to the Si\u2013O\u2013Si units. Its characteristic relaxation time is 5.6 s at 220 \u00b0C, the fastest siloxane exchange reported, with an activation energy of 87.2 \u00b1 0.9 kJ mol\u207b\u00b9 and a glass transition temperature near 85 \u00b0C. Thermogravimetry places 5% mass loss at 350 \u00b0C, and an isothermal hold at 220 \u00b0C for one hour costs about 1% of the mass. The network was mechanically reprocessed three times, recovering a relaxation time of roughly 6 s, a DSC Tg of 85 \u00b0C, and a soluble fraction near 1% on each occasion.

\n

The practical significance lies in the viscosity. The formulation measures 300 mPa\u00b7s at 25 \u00b0C, lower than commercial epoxy resins of comparable Tg, and it stays low for more than an hour of mixing. That allowed the authors to impregnate eight plies of plain-woven glass fabric at 220 g m\u207b\u00b2 by vacuum-assisted resin infusion, the technique used to manufacture wind turbine blades, and then to thermoform the cured laminate at 190 \u00b0C under 30 bar. A cured glass-fibre composite that can be reshaped after manufacture is a genuinely new object.

\n

Direct Silyl Ether Metathesis: Vitrimers Without Free Hydroxyl Groups

\n

The second route to dynamic Si\u2013O chemistry comes from Zhibin Guan's laboratory at UC Irvine, where Chase Tretbar, James Neal, and Guan reported the first example of direct silyl ether metathesis in JACS in 2019. The advance over earlier silyl ether systems is the removal of free hydroxyl groups from the network. Previous designs required a free alcohol as the exchange partner, and at elevated temperature alcohols open the door to dehydration, oxidation, and transesterification with acrylate backbones. Ether to ether metathesis avoids the problem entirely.

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The reaction was established on small molecules by mixing ethyltributoxysilane and ethyltripentoxysilane in anhydrous solvent and following the approach to the statistical 1:3:3:1 distribution of the four possible silanes by GC-MS. Without catalyst, full equilibration required 16.5 hours at 190 \u00b0C. Camphorsulfonic acid at 5 mol% proved the most effective of the catalysts tested, which also included zinc and scandium triflates. The polymer was then built from commodity material: poly(ethylene-co-vinyl acetate) with 6 mol% vinyl acetate was hydrolyzed quantitatively with sodium methoxide and the resulting alcohols were silylated with N,O-bis(trimethylsilyl)acetamide to give a trimethylsilyl ether functional polyethylene. Crosslinking used bis(methoxydimethyl)silyl octane, itself made in one step from the corresponding bis(chlorodimethyl)silyl octane and methanol, at 3 mol% of the available OTMS groups with 2 mol% camphorsulfonic acid, and gelation occurred in toluene at 80 \u00b0C.

\n
\"Silyl
Fig. 7. Two strategies for silyl ether dynamics. (A) Silyl ether\u2013hydroxyl exchange requires a free alcohol as the partner, and at elevated temperature that alcohol opens pathways to dehydration, oxidation, and transesterification. (B) Direct metathesis proceeds between two silyl ethers with no free alcohol involved, so the network loses its most reactive component while the Si\u2013OR motif remains thermally and oxidatively robust. This difference is what yields a vitrimer whose 5% mass loss occurs only at 427 \u00b0C. Redrawn from: Tretbar, C. A.; Neal, J. A.; Guan, Z. J. Am. Chem. Soc. 2019, 141, 16595. DOI: 10.1021/jacs.9b08876, Fig. 1.
\n

With a Si\u2013O bond dissociation energy near 535 kJ mol\u207b\u00b9 and no reactive hydroxyls present, the resulting vitrimer loses 5% of its mass only at 427 \u00b0C, which the authors identify as the highest value reported for a vitrimer at the time of publication in 2019. The activation energy for exchange is 77.8 kJ mol\u207b\u00b9, the topology-freezing temperature is 45 \u00b0C, and crosslinking raises the Young's modulus fivefold from 19.2 \u00b1 1 to 101 \u00b1 19 MPa. The cost of that stability appears in the kinetics: relaxation times run from 6456 s at 130 \u00b0C to 770 s at 170 \u00b0C.

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Comparing Si\u2013O Exchange Kinetics: Siloxane, Silyl Ether and Ester Vitrimers

\n

Placing the three systems on common axes, with the unfilled epoxy network as a baseline, makes the trade-off explicit. Each line below is an Arrhenius extrapolation anchored at a single published point using the reported activation energy, so the comparison rests on measured values rather than on digitized curves.

\n
\"Arrhenius
Fig. 8. The landscape of dynamic Si\u2013O exchange in vitrimers. TBD-catalyzed siloxane exchange (\u03c4* = 5.6 s at 220 \u00b0C) is more than two orders of magnitude faster than silyl ether metathesis (\u03c4* = 770 s at 170 \u00b0C), which in turn offers unmatched thermal stability (Td,5% = 427 \u00b0C). Transesterification in the epoxy\u2013POSS network is the slowest of the three up to roughly 175 \u00b0C, crossing below silyl ether metathesis only above that temperature. The fourth line is the unfilled epoxy vitrimer from the same study, shown as a baseline for what the cage changes. Markers are published values; lines are Arrhenius extrapolations from the reported activation energies. Compiled from three studies: Debsharma, T. et al. J. Am. Chem. Soc. 2022, 144, 12280. DOI: 10.1021/jacs.2c03518; Tretbar, C. A.; Neal, J. A.; Guan, Z. J. Am. Chem. Soc. 2019, 141, 16595. DOI: 10.1021/jacs.9b08876; Yang, H. et al. Giant 2020, 4, 100035. DOI: 10.1016/j.giant.2020.100035.
\n

Only the TBD-catalyzed siloxane system enters the window below 60 s where industrial compression molding becomes practical. Silyl ether metathesis buys thermal stability at the price of roughly three orders of magnitude in rate, and the epoxy\u2013POSS transesterification network, with the highest activation energy of the three at 107.9 kJ mol\u207b\u00b9, is the most temperature-sensitive and therefore the one whose processing window is most sharply defined.

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Octaglycidyl POSS in a Disulfide-Exchange Silicone Vitrimer

\n

One study has already brought the two worlds together, although it was not framed that way. Cheng'e Yue and co-workers at Harbin University of Science and Technology published a vitrimeric silicone composite for thermal interface applications in the Journal of Colloid and Interface Science in 2022. The matrix is a siloxane epoxide, prepared by Karstedt-catalyzed hydrosilylation of allyl glycidyl ether with 1,1,3,3-tetramethyldisiloxane, cured with 4-aminophenyl disulfide so that aromatic disulfide metathesis supplies the dynamic chemistry. The filler is boron nitride nanosheets, exfoliated by sonication, hydroxylated, and surface-modified with (3-glycidoxypropyl)trimethoxysilane to improve compatibility with the matrix. The third component is octaglycidyl POSS, the same cage and the same supplier as in the Yang study, blended at a DGESi:APDS:POSS weight ratio of 100:60:x and cured at 150 \u00b0C for two hours in air.

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\"Synthesis
Fig. 9. Construction of the vitrimeric silicone composite. Hydrosilylation of 1,1,3,3-tetramethyldisiloxane with allyl glycidyl ether over Karstedt's catalyst gives the difunctional siloxane epoxide DGESi, which is then cured with 4-aminophenyl disulfide in the presence of octaglycidyl POSS. In the resulting network the POSS cage acts as a junction while the aromatic disulfide bridges carry the dynamics, and it is their exchange that provides self-healing and reprocessability. Redrawn from: Yue, C.; Zhao, L.; Guan, L.; Zhang, X.; Qu, C.; Wang, D.; Weng, L. J. Colloid Interface Sci. 2022, 620, 273. DOI: 10.1016/j.jcis.2022.04.017, Fig. 1a.
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At 10 wt% POSS the tensile strength increases 2.82-fold to 8.4 \u00b1 0.1 MPa. The thermally conductive composites were built on the POSS-5 matrix rather than POSS-10, and with 66 wt% functionalized boron nitride their thermal conductivity reaches 1.41 \u00b1 0.05 W m\u207b\u00b9 K\u207b\u00b9, more than six times that of the unfilled elastomer, and the healing efficiency remains at 92.0 \u00b1 1.5% against 98.8 \u00b1 1.1% for the unfilled matrix. Thermal conductivity recovers to 99.3% of its original value after six healing cycles.

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The detail most easily missed concerns the glass transition. In this work POSS raises Tg from 45.4 \u00b1 0.2 to 51.1 \u00b1 0.4 \u00b0C, whereas in the Yang study it lowered Tg. The same cage, from the same supplier, produces opposite effects in two different matrices, because the network topology and the mode of incorporation differ. That single observation is a compact statement of how much remains unexamined.

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Can the T8 Cage Backbone Itself Be the Exchange Site?

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The established facts can be summarized briefly. The silicon\u2013oxygen bond is thermodynamically strong at roughly 535 kJ mol\u207b\u00b9 and kinetically labile under the right conditions, a combination that makes it an excellent dynamic motif. It can be exchanged quickly, in 5.6 s with TBD and a hydroxyl partner, or exchanged with exceptional stability, surviving to 427 \u00b0C through silyl ether metathesis. The T8 cage incorporated as a filler into a vitrimer network raises strength and ductility simultaneously, increases Tv, and decouples creep resistance from processability.

\n

What has not been examined is what happens when the cage stops being a filler and becomes the carrier of the dynamic chemistry. In all three network studies the cage is an additive. It sits in the network, it raises the crosslink density, and it modifies the mechanical response, but the exchange happens somewhere else: on the ester bonds of the matrix, on the disulfide bridges, on the siloxane units of the hardener. The cage is a passive junction in a dynamic network.

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It is worth separating three levels at which a cage can participate. At the first level the cage is a nanoscale filler and the exchange happens entirely in the surrounding matrix, which is what every study described above actually demonstrates. At the second level the cage becomes a multifunctional covalent junction whose vertices carry the dynamic groups, and this has been explored in part, since the glycidyl arms in the Yang network do sit adjacent to the exchanging esters. The third level has not been reached at all, and it is the one where the Si\u2013O\u2013Si bridges of the cage framework themselves take part in associative exchange.

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That third level is not an exotic proposal. The T8 cage is built from twelve Si\u2013O\u2013Si bridges, structurally the same linkage that Du Prez and co-workers exchange in 5.6 s. The question it raises, and one that appears not to have been put, is whether a silsesquioxane cage in the presence of TBD and hydroxyl groups becomes a dynamic junction in its own right, so that the cage framework rather than its substituents carries the topology rearrangement.

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A positive result is not guaranteed, and the structural arguments cut both ways. The Si\u2013O\u2013Si angles in the cubic cage are strained relative to linear siloxanes, which could make the bridges more susceptible to nucleophilic attack and therefore faster to exchange. The same strain, however, means that an opened cage has no straightforward route back to the closed structure, so exchange could lead to irreversible cage opening and condensation into ladder or resinous architectures rather than to clean associative exchange. The cage might also simply be unreactive on the timescale of the experiment, since the bridging oxygens are sterically shielded by eight substituents pointing outward from the vertices.

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A Silicon-29 NMR Control Experiment to Test POSS Cage Exchange

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The first question to settle is narrow and cheap to answer. Octaglycidyl POSS, or any soluble T8 cage, is held at 220 \u00b0C in the presence of 10 mol% TBD and a hydroxyl source under the conditions that produce fast siloxane exchange in the Du Prez system, and the cage is monitored by silicon-29 NMR. Every silicon in a closed T8 cage carries three siloxane bridges, so the cage is a T\u00b3 species and gives a single symmetric resonance; the Wroc\u0142aw group reports \u221266.2 ppm for their octa-functionalized cages, and values between roughly \u221266 and \u221270 ppm are typical for alkyl-substituted cages. Survival of the cage would show that one resonance persisting throughout. Opening a bridge converts two silicons from T\u00b3 to T\u00b2, and those T\u00b2 signals appear well downfield of the cage, in the region around \u221256 to \u221260 ppm. Cage opening would therefore announce itself as new T\u00b2 intensity, loss of the symmetry that makes all eight silicon atoms equivalent, and in the limit a broad envelope characteristic of a condensed resin.

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Either outcome is informative. If the cage survives, the next experiment is a crossover study with two differently substituted cages, following the design Debsharma and co-workers used for their disiloxane model compounds, to establish whether exchange occurs at the cage framework at all. If the cage opens, the result sets a clear boundary on how aggressive the catalysis can be in any POSS vitrimer and explains why cage-based dynamic networks have not appeared. The reagents are commercial, the instrumentation is standard, and the experiment occupies an afternoon.

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Outlook: Where POSS and Vitrimer Chemistry Meet Next

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Taken together, these five studies describe a field in which two mature chemistries have remained almost entirely separate. Vitrimer design has converged on the silicon\u2013oxygen bond as one of its most capable dynamic motifs, and silsesquioxane chemistry provides the most precisely defined Si\u2013O architecture available, a monodisperse cage with eight equivalent vertices and twelve equivalent bridges. The only published point of contact treats the cage as a filler, and even in that role it decouples properties that are otherwise coupled. Whether the cage can also serve as the exchange site is an open structural question with a cheap first experiment and a publishable answer in either direction.

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A second pattern runs through these studies. Dynamic Si\u2013O chemistry connects applications that appear unrelated, from the reshaping of glass-fibre composites destined for wind turbine blades to the thermal management of integrated circuits, and in each of them the silsesquioxane cage appears as the least examined variable. That is usually a sign of where the next result is to be found.

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Frequently Asked Questions About POSS Vitrimers

What is a POSS vitrimer?

A POSS vitrimer is a covalent adaptable network in which polyhedral oligomeric silsesquioxane cages are built into a vitrimer matrix. The network rearranges its topology by associative exchange, so the crosslink density never drops, while the T8 cage acts as a rigid, molecularly dispersed, eight-arm junction. In every published example the exchange chemistry itself sits in the matrix rather than on the cage.

Does POSS make a vitrimer stronger or more brittle?

Both strength and ductility improve, which is unusual for a filled network. At 10 wt% loading the tensile strength rises 63.5% and the strain at break 75.8%. The eight glycidyl arms raise the crosslink density while the nanoporous cage absorbs deformation energy. The Young's modulus and the glass transition temperature fall slightly.

How fast is siloxane exchange compared with other vitrimer chemistries?

TBD-catalyzed Si\u2013O\u2013Si exchange relaxes in 5.6 s at 220 \u00b0C, which puts it inside the window for industrial compression molding. Direct silyl ether metathesis is roughly three orders of magnitude slower (770 s at 170 \u00b0C) but survives to 427 \u00b0C. Hydroxyl\u2013ester transesterification in the epoxy\u2013POSS network is the slowest of the three below about 175 \u00b0C.

Can the Si\u2013O\u2013Si bridges of the T8 cage act as dynamic bonds?

Nobody has tested it. The cage contains twelve Si\u2013O\u2013Si bridges, structurally the same linkage that exchanges in 5.6 s under TBD catalysis, but the strained cage geometry could equally lead to irreversible ring opening. A silicon-29 NMR experiment on a soluble T8 cage held with TBD and a hydroxyl source would settle the question in an afternoon.

References

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  1. Yang, H.; He, C.; Russell, T. P.; Wang, D. Epoxy-polyhedral oligomeric silsesquioxanes (POSS) nanocomposite vitrimers with high strength, toughness, and efficient relaxation. Giant 2020, 4, 100035. DOI: 10.1016/j.giant.2020.100035
  2. Debsharma, T.; Amfilochiou, V.; Wr\u00f3blewska, A. A.; De Baere, I.; Van Paepegem, W.; Du Prez, F. E. Fast Dynamic Siloxane Exchange Mechanism for Reshapable Vitrimer Composites. J. Am. Chem. Soc. 2022, 144, 12280\u201312289. DOI: 10.1021/jacs.2c03518
  3. Tretbar, C. A.; Neal, J. A.; Guan, Z. Direct Silyl Ether Metathesis for Vitrimers with Exceptional Thermal Stability. J. Am. Chem. Soc. 2019, 141, 16595\u201316599. DOI: 10.1021/jacs.9b08876
  4. Yue, C.; Zhao, L.; Guan, L.; Zhang, X.; Qu, C.; Wang, D.; Weng, L. Vitrimeric silicone composite with high thermal conductivity and high repairing efficiency as thermal interface materials. J. Colloid Interface Sci. 2022, 620, 273\u2013283. DOI: 10.1016/j.jcis.2022.04.017
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  6. Montarnal, D.; Capelot, M.; Tournilhac, F.; Leibler, L. Silica-Like Malleable Materials from Permanent Organic Networks. Science 2011, 334, 965\u2013968. DOI: 10.1126/science.1212648
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  10. Cieplucha, M.; Janeta, M.; Szafert, S. Hybrid inorganic\u2013organic polyhedral oligomeric silsesquioxane-based poly(1-haloacetylene)s: thermal, solid-state polymerization. Materials Chemistry Frontiers 2025, 9, 3034. DOI: 10.1039/d5qm00583c
  11. Abad, M. J.; Barral, L.; Fasce, D. P.; Williams, R. J. J. Epoxy networks containing large mass fractions of a monofunctional polyhedral oligomeric silsesquioxane (POSS). Macromolecules 2003, 36, 3128\u20133135. DOI: 10.1021/ma021539f
  12. Fuchise, K.; Igarashi, M.; Sato, K.; Shimada, S. Organocatalytic controlled/living ring-opening polymerization of cyclotrisiloxanes initiated by water with strong organic base catalysts. Chem. Sci. 2018, 9, 2879\u20132891. DOI: 10.1039/c7sc04234e
","doi":"https://doi.org/10.59350/ertwn-adj25","guid":"tag:blogger.com,1999:blog-2875892712213933214.post-9005552109808412174","image":"https://blogger.googleusercontent.com/img/a/AVvXsEi9ZS55ploFdjdsNDBqaBK2PhqAUScoMkQdZLdFHaQo-4_05p8JujbQBHuM7Z5mu5IywPe7umOukX8Iuq7L8Xrk3IK54aDd8yPqfQo5sKZWv2WSl9gDhzDrqFaQ_ks82crBdsD1FEBsjy2hP38qRIA_BTksmxO1WohBP2W7E1rhk3TfgTZVGtgEdTXVsxI=s72-c","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790985600,"reference":[{"id":"https://doi.org/10.1016/j.giant.2020.100035","unstructured":"Yang, H., He, C., Russell, T. P., & Wang, D. (2020). Epoxy-polyhedral oligomeric silsesquioxanes (POSS) nanocomposite vitrimers with high strength, toughness, and efficient relaxation. Giant, 4, 100035."},{"id":"https://doi.org/10.1021/jacs.2c03518","unstructured":"Debsharma, T., Amfilochiou, V., Wr\u00f3blewska, A. A., De Baere, I., Van Paepegem, W., & Du Prez, F. E. (2022). Fast Dynamic Siloxane Exchange Mechanism for Reshapable Vitrimer Composites. Journal of the American Chemical Society, 144(27), 12280\u201312289."},{"id":"https://doi.org/10.1021/jacs.9b08876","unstructured":"Tretbar, C. A., Neal, J. A., & Guan, Z. (2019). Direct Silyl Ether Metathesis for Vitrimers with Exceptional Thermal Stability. Journal of the American Chemical Society, 141(42), 16595\u201316599."},{"id":"https://doi.org/10.1016/j.jcis.2022.04.017","unstructured":"Yue, C., Zhao, L., Guan, L., Zhang, X., Qu, C., Wang, D., & Weng, L. (2022). Vitrimeric silicone composite with high thermal conductivity and high repairing efficiency as thermal interface materials. Journal of Colloid and Interface Science, 620, 273\u2013283."},{"id":"https://doi.org/10.1039/c5sc02223a","unstructured":"Denissen, W., Winne, J. M., & Du Prez, F. E. (2016). Vitrimers: permanent organic networks with glass-like fluidity. Chemical Science, 7(1), 30\u201338."},{"id":"https://doi.org/10.1126/science.1212648","unstructured":"Montarnal, D., Capelot, M., Tournilhac, F., & Leibler, L. (2011). Silica-Like Malleable Materials from Permanent Organic Networks. Science, 334(6058), 965\u2013968."},{"id":"https://doi.org/10.1073/pnas.0911705106","unstructured":"Mauro, J. C., Yue, Y., Ellison, A. J., Gupta, P. K., & Allan, D. C. (2009). Viscosity of glass-forming liquids. Proceedings of the National Academy of Sciences, 106(47), 19780\u201319784."},{"id":"https://doi.org/10.1021/ja2113257","unstructured":"Zheng, P., & McCarthy, T. J. (2012). A Surprise from 1954: Siloxane Equilibration Is a Simple, Robust, and Obvious Polymer Self-Healing Mechanism. Journal of the American Chemical Society, 134(4), 2024\u20132027."},{"id":"https://doi.org/10.1016/j.polymer.2020.123126","unstructured":"Hajiali, F., Tajbakhsh, S., & Mari\u0107, M. (2021). Thermally reprocessable bio-based polymethacrylate vitrimers and nanocomposites. Polymer, 212, 123126."},{"id":"https://doi.org/10.1039/d5qm00583c","unstructured":"Cieplucha, M., Janeta, M., & Szafert, S. (2025). Hybrid inorganic\u2013organic polyhedral oligomeric silsesquioxane-based poly(1-haloacetylene)s: thermal, solid-state polymerization. Materials Chemistry Frontiers, 9(20), 3034\u20133043."},{"id":"https://doi.org/10.1021/ma021539f","unstructured":"Abad, M. J., Barral, L., Fasce, D. P., & Williams, R. J. J. (2003). Epoxy Networks Containing Large Mass Fractions of a Monofunctional Polyhedral Oligomeric Silsesquioxane (POSS). Macromolecules, 36(9), 3128\u20133135."},{"id":"https://doi.org/10.1039/c7sc04234e","unstructured":"Fuchise, K., Igarashi, M., Sato, K., & Shimada, S. (2018). Organocatalytic controlled/living ring-opening polymerization of cyclotrisiloxanes initiated by water with strong organic base catalysts. Chemical Science, 9(11), 2879\u20132891."}],"rid":"yba07-a3p15","summary":"Epoxy nanocomposite vitrimers containing polyhedral oligomeric silsesquioxane (POSS) were reported by Hongkun Yang, Changfei He, Thomas P. Russell, and Dong Wang in Giant in 2020. Studies devoted specifically to POSS in vitrimer networks remain scarce, and this one still carries the subject almost on its own.","tags":["Covalent Adaptable Network","Dynamic Covalent Chemistry","POSS","Siloxane Exchange","Silsesquioxane"],"title":"POSS Vitrimers: The Cage as a Dynamic Si\u2013O\u2013Si Node","updated_at":1791045319,"url":"https://silsesquioxane.blogspot.com/2026/10/poss-vitrimers-dynamic-siloxane-cage.html","version":"v1"},{"authors":[{"contributor_roles":[],"family":"Fix","given":"Blair"}],"blog":{"authors":null,"community_id":"0b9cb48f-680d-4f11-99f0-5b61a55fe4cc","created":1714262400,"current_feed_url":null,"description":"New ideas in economics and the social sciences","doi":"https://doi.org/10.59350/etd","favicon":"https://rogue-scholar.org/api/communities/0b9cb48f-680d-4f11-99f0-5b61a55fe4cc/logo","feed_format":"application/atom+xml","feed_url":"https://economicsfromthetopdown.com/feed/atom/","filter":null,"generator":"Other","home_page_url":"https://economicsfromthetopdown.com/","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"etd","status":"active","subfield":"2002","title":"Economics from the Top Down","updated":1791029100,"use_api":true},"blog_name":"Economics from the Top Down","blog_slug":"etd","content_html":"\"\"
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Given our current landscape of AI hype and doom, everyone seems to have an opinion about whether chatbots are 'good' or 'bad'. Fewer people have thought about how chatbots fit into the long-term history of automation. And even fewer folks have reflected on the conceptual requirements that make automation useful. Here are my thoughts on this latter topic.

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In my view, automation is useful when it meets two criteria:

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  1. The product is more important than the process that creates it.\n
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  2. The product can be validated without auditing the creation process.\n
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If we look at successful forms of machine automation, they tend to meet both criteria. For example, think of a pencil factory that automates the production of pencils. Here, the pencil is the 'product', and whatever happens inside the factory is the 'process'.

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Now for the end user, the process of pencil production is largely irrelevant. It doesn't matter if the pencil is hand crafted, built in an assembly line, or conjured by a Star Trek replicator. As long as the pencil works in the hands of the user, its creation process is unimportant.

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That brings me to the second requirement for useful automation: the product must be easily validated. To validate that a pencil works, you don't need to audit the process that created it. You just give the thing a go. Yup, this pencil works. Nope, that one's a dud.

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Thinking more broadly, the history of automation has been dominated by this sort of process where a machine replaces human labor in the production of some sort of physical commodity. The automation works because (1) the commodity is valued more than the process that creates it, and (2) it's easy to verify the quality of the commodity without auditing the entire chain of production.

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Intellectual automation

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Looking to more recent technological progress, it turns out that successful automation need not be physical. Intellectual automation can also be useful. Just look at computers, which owe their name to the desire to automate computation.

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Many forms of computation pass our automation requirements: the product is more important than the process, and the process is easy to validate. For example, when I ask a computer to calculate \\sqrt{200} , I don't care about the algorithm it uses, or about the details of its chipset. I just want the answer. Likewise, once I have the result, I don't have to audit the computer's innards to validate the answer. I just check that the number squares to give 200.

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In more general terms, any intellectual task that meets our two requirements is game for computer automation. But for years, some forms of intellectual work seemed beyond the reach of computers. Writing code is a good example. Historically, programming was a tedious task that took years of specialized training. But with the rise of neural nets and their associated chatbot interfaces, these barriers are being torn down. Chatbots can now code more quickly than any human. But is this ability useful?

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Well, the answer depends on whether the application passes our two requirements. (Is the product more important than the process? And can the product be verified without auditing the process that created it?) Clearly, many forms of coding pass this test. Web design is an obvious example. When a blogger asks for a nice website, they usually don't care how it's accomplished. Likewise, the blogger can easily tell if the final design is what they want. (They just browse the website.)

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In short, chatbots are useful for automating intellectual tasks like web design (and any other easily verified piece of software). Yes, the bots will put some folks out of work. Yes, they'll raise questions about the skills required in the workforce. And yes, they'll be used in ways that undermine labor power and harm workers' health. But these issues are nothing new. They're a historical feature of all forms of automation. What interests me more (at least in this essay) is the ways in which chatbot automation might be fundamentally useless, or even downright harmful.

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On the useless front, I'm skeptical that chatbots can be used to fully automate scientific analysis. Here's why. When a scientist analyzes their data, they might think that the product of their inquiry is the 'results' section in their published paper. And in some sense, that's true. But the (big) caveat is that the usefulness of this result depends on whether the analysis pipeline is correct.

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Now, suppose that a scientist automated their work by getting a chatbot to code the entirety of their analytic pipeline. How does the scientist know that their results are correct?1 Well, if the analysis is complicated, the only sound way to assess its correctness is to audit the underlying code. That requires significant time and skill. Meanwhile, this time-skill investment largely defeats the purpose of automation. Of course, chatbots can no doubt help scientist solve specific coding problems. (These bots lower the barrier to successful programming.) But the notion that chatbots will fully automate scientific analysis is, frankly, laughable.

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True, some academics will surely try this fully automated approach. In fact, I expect that the scientific literature will become increasingly polluted with bot junk. But I'd argue that we can't blame chatbots (solely) for this pollution. The root problem is the incentive structure in universities \u2014 a structure that values the production of academic papers far more than the process that creates them. But when it comes to good research, its social value lies entirely in the scientific process.

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Process dependence

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Like science, many areas of human life have a process dependence, in which the usefulness of a 'product' hinges solely on the process of doing it. Schooling is the most ubiquitous example. When a teacher asks students to solve a math problem, the product of this task is the correct answer. But the usefulness of this activity lies mostly in the process of doing it. Sure, a calculator will tell you the sum of 21 + 54. But if the goal is to learn basic arithmetic, the use of a calculator is not 'automation'. It's cheating.

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The obvious conclusion is that skill acquisition cannot be automated. If the goal is to learn basic arithmetic, a calculator is self-defeating. If the goal is learn to the principles of English spelling, a spell checker is unhelpful. If the goal is to learn to read, a text-to-voice processor is educational sabotage. And if the goal is to learn to write, well, chatbots are your mortal enemy.2

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In this light, we can think of formal education as a teaching method that forces students to re-experience, in a curated and abbreviated form, problems that long stumped our ancestors. For example, it took thousands of years of doing arithmetic before humans automated the job with calculators. By then, mathematics was a mature field. When today's students learn math, they replay this history over the course of a few years. At first, 'math' consists solely of raw computation. Later on, students learn more symbolic logic, and the number crunching gets delegated to machines. In short, when it comes to intellectual automation, everything hinges on the order of operations. First, you learn a difficult skill; then you discover that you can automate it.

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Do not automate

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Thinking further about process dependence, it seems likely that some intellectual tasks should never be automated. Writing is the most obvious example.

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To understand why automated writing is bad, we need to first deal with the overloaded nature of the English language. In English, the word 'write' has a misleading double meaning. In one sense, to 'write' means to 'scribe' \u2014 to put an already existing sentence onto paper. This form of 'writing' takes skill, but is grounds for useful automation. Once upon a time, video captions were transcribed by a human listener. But today, the captioning can be generated by natural language processors.

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The problem with automated 'writing' comes with the second meaning of the word. To 'write' is not just to scribe; it's also to craft a set of coherent arguments that other humans can follow and understand. To automate this activity is an oxymoron, because the product (a rational argument) can't be separated from the process itself. Or as my mentor Jonathan Nitzan once told me, \"You don't really know what you think until you write it down.\"

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Here's what he means. 'Writing', in this sense of the word, is essentially codified thinking. When an idea is written down, reading this idea leads to all kinds of interesting consequences. Often, the writer realizes that the idea is vague or incomplete. And so they revise it until things make sense. Once the idea is coherent, rereading it prompts new ideas and new connections. Many are dead ends. Some are fruitful.

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To be frank, this iterative process can be torturous. When I write blog posts about my research, the final essay usually conceals an iceberg of revised or discarded thought. Sure, I'd like to avoid this torture and still have the final well-argued essay. But to avoid the torture of 'writing' is to avoid the discomfort of rational thought. Automating this task does not 'save time'; it saves us from thinking.

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Automation for whom?

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For automation to be 'useful', the product must be more important than the process by which it is created. But there is a sticky question that I've so far avoided: more important for whom?

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For the user of a pencil, the way that this commodity was manufactured is largely irrelevant. But for the folks who live beside the pencil factory, the manufacturing process is often more salient than the product itself, particularly if pollution is involved. Likewise, chatbots might be great for the Silicon Valley programmer, but they're a Faustian bargain for the utility planners who have to power local data centers.

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When it comes to the big picture of automation, the process by which it occurs is incredibly consequential \u2026 often far more so than the product being automated. It's one thing to have a Star-Trek-like computer powered by nuclear fusion; it's quite another to have a sycophantic chatbot powered by fossil fuels.

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Unfortunately, we humans are notoriously bad at assessing the big-picture consequences of our automation schemes. As a rule, we build first and ask questions later. Today, we seem to be automating tasks that should not be automated (using fuels that are steadily spoiling the planet). The internet is increasingly littered with chatbot slop, to the point that search engines can feel pointless. If a search query returns page after page of bot slop, it's obviously more sensible to pose the question directly to a chatbot. But if the chatbot is trained on bot-slop, how can you trust its answer?

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Now, I'm personally skeptical of claims about AI-driven doom, but mostly because they go in the wrong direction. If there's a risk that AI will kill industrial civilization, it's not because the machines will take over. Far more likely, in my opinion, is that we get a future that looks like an anti-singularity \u2014 a future in which our technology becomes so powerful (and so polluting) that it gradually undermines its own existence. As humans subcontract thinking to fossil-fuel-fed chatbots, the information environment (as well as the natural environment) becomes polluted with slop, and the slop-trained bots themselves grow increasingly senile. \"Water the crops with Brawndo,\" the bots say. Meanwhile, AI-driven education has left humans gullible enough to listen.3

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In short, automation can be useful if it frees us from drudgery (in a way that doesn't destroy the earth) and leaves more time for creative thought. But if automated chatbots gobble fossil fuels in order to liberate us from thinking, well, civilization had a nice run.

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Support this blog

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Hi folks, Blair Fix here. I'm a crowdfunded scientist who shares all of my (painstaking) research for free. If you think my work has value, consider becoming a supporter. You'll help me continue to share data-driven science with a world that needs less opinion and more facts.

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This work is licensed under a Creative Commons Attribution 4.0 License. You can use/share it anyway you want, provided you attribute it to me (Blair Fix) and link to Economics from the Top Down.

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Notes

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  1. Of course, the truth is that even the best-trained scientists make mistakes, which is why good science requires replication. And regarding code, there's an old saying that you shouldn't reinvent the wheel \u2026 don't recode an algorithm that someone has already solved. Which is why scientific code is typically full of libraries and functions which the scientist in question did not write.\n

    For example, when I get R to calculate a matrix inverse, I'm actually calling ancient Fortran code for doing linear algebra. To me, this code is a black box \u2014 I have no idea how it works. So how do I know that this code works correctly? Honestly, it's a matter of trust. These libraries are free and open source, and have been used for ages. If they had a gaping problem, scientists would not use them.

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    Now, this game of trust comes on a continuum. I greatly trust R's matrix inverse functions. I put less trust in code from a random Github repository. And I put even less trust in the code delivered by a chatbot. Sure, the chatbot code may be 99% good. But that 1% bad stuff can be a killer. Imagine a world in which all scientific analysis and all scientific libraries were coded by chatbots with no supervision from scientists. Each time a bot calls a Python or R library, there's a 1% chance of error. As the code expands, the error compounds, to the point that virtually everything the bots spit out is wrong.

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    Still, chatbots shine in the domain where automation has always been useful \u2014 when the results are easily verifiable. Refactoring code is a good example. If I do an analysis in R and someone else wants to refactor the code into Python, a chatbot could make short work of the task. Sure, the chatbot might make mistakes along the way, but the user could tell by comparing the R output to the Python output.\"\u21a9\"\ufe0e\n

    2. \n
  2. In schools systems, teachers often speak in the language of 'accommodations' \u2014 as in text-to-voice is an 'accommodation' for dyslexia. While this use of technology is well intentioned, it's also tragic. The truth is that if a teenager cannot read effectively, all available resources should go into solving this highly solvable problem. In my view, it's unethical to forge ahead with other curriculum in the face of gaping illiteracy.\"\u21a9\"\ufe0e\n
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  3. If there are long-term benefits to chatbots, they will come by strategically withholding chatbot use while students learn difficult and uncomfortable skills. Actually using a chatbot takes about as much skill as using a calculator. Which is funny, because no one would propose a 'calculator-driven education'. But many folks will claim that AI is going to revolutionize schooling. Well, I work in high schools and can tell you that so far, what's been 'revolutionary' is that chatbots have killed the take-home essay. Learning to craft long-form thought used to be a standard feature of high-school education. Now it's not.\"\u21a9\"\ufe0e\n
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Further reading

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\nDoctorow, C. (2026). The reverse centaur's guide to life after AI: How to think about artificial intelligence before it's too late. Verso Books.\n

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The post The Laws of Useful Automation appeared first on Economics from the Top Down.

","doi":"https://doi.org/10.59350/rgz3a-njq17","guid":"https://economicsfromthetopdown.com/?p=15696","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790985600,"rid":"m3k2b-jkd40","summary":"Your browser does not support the audio tag. Download: PDF | EPUB | MP3 | WATCH VIDEO Given our current landscape of AI hype and doom, everyone seems to have an opinion about whether chatbots are 'good' or 'bad'. Fewer people have thought about how chatbots fit into the long-term history of automation. And even fewer folks have reflected on the conceptual requirements that make automation useful. Here are my thoughts on this latter topic.","tags":["Academic Work","AI Doom","AI Hype","Anti-singularity","Automation"],"title":"The Laws of Useful Automation","updated_at":1791029107,"url":"https://economicsfromthetopdown.com/2026/10/03/the-laws-of-useful-automation/","version":"v1"},{"authors":[{"contributor_roles":[],"family":"Baroncini","given":"Sofia"}],"blog":{"authors":null,"community_id":"be4c775e-c004-4189-8322-25abe1cc96c9","created":1737676800,"current_feed_url":null,"description":"Leibniz Institute of European History (IEG)","doi":null,"favicon":"https://rogue-scholar.org/api/communities/be4c775e-c004-4189-8322-25abe1cc96c9/logo","feed_format":"application/atom+xml","feed_url":"https://dhlab.hypotheses.org/feed/atom/","filter":null,"generator":"WordPress","home_page_url":"https://dhlab.hypotheses.org","issn":null,"language":"deu","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":null,"relative_url":null,"secure":true,"slug":"dhlab","status":"active","subfield":"1202","title":"DH Lab","updated":1790323745,"use_api":true},"blog_name":"DH Lab","blog_slug":"dhlab","content_html":"

Introduction: What is an ontology?

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Everything we can do on a computer is encoded; namely, a sequence of 0-1 bits is associated with symbolic content. This is the core fundamental principle allowing us to do a range of different operations on a computer, from writing a document in Word to viewing an image.

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If everything can be encoded through this kind of association, then machines can compute meanings as well. Since the 1950s, the branch of symbolic AI has researched the possibility of doing a detailed description of the world, in the form of concepts and relations, and associating them with logical rules. In this way, a computer could do sophisticated operations, such as inferring knowledge not directly stated in the data. For example, if the data states that Sonia is the sister of Juliette and Alice, and the relation is declared as being transitive, then the system could infer that Juliette and Alice are sisters, too.

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One application of this approach is ontologies, in other words, a structured way, processable by computers, of describing a particular domain of knowledge. It identifies the main concepts in that domain and, most importantly, the relationships between them. For example, in a project about works of art, an ontology might define concepts such as Person, Artwork, the Creation Event, Institutions holding the artwork, the Iconography depicted, and so on. In this sense, an ontology does more than provide a list of terms. It provides a shared conceptual framework that helps both humans and computers understand how different pieces of information are connected.

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Furthermore, an ontology can also state logical rules allowing the system to infer further information, or to check that data is described correctly. For example, in Figure 1, the ontology states that the concept \"Artist\" is a subclass of \"Person\". If, in the dataset, \"Monet\" is described as \"Artist\", the computer, through a reasoner (i.e., a software tool that automatically checks the logical consistency of the ontology and derives new facts from it), can infer that Monet is not only an artist, but also a person. This means that in a dataset in which all people are described according to their profession, and all the professions are stated as a subclass of \"Person\", we can easily retrieve all the people in the dataset although none of them is explicitly described as a person.

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\"Figure
Figure 1. Example of how an ontology can be used to infer further knowledge. If in the graph dataset I insert the information that Monet is an Artist, and the ontology \"Artist\" is stated as being subclass of \"Person\", then the computer can infer that Monet is also a \"Person\", without the need to manually enter that information. Figure by Sofia Baroncini
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A key concept is the distinction between the ontology itself, defining classes or concepts, and data described according to that ontology, representing individuals or instances (see Figure 2). Whereas the first describes how the types of entities relate to each other and represents the domain in abstract terms (e.g., \"Artist\" is a subclass of \"Person\"), the latter contains the actual content (\"Monet\"). In other words, it is similar to the difference between an Excel sheet showing only the column names and the same sheet filled with actual data: the columns give us information about how the data is organized (\"People\"), whereas the rows are the actual individuals (\"Monet\", \"Picasso\", etc.). In ontology development, these are also called \"T-BOX\" and \"A-BOX\". The actual content needs to follow the structure defined in the ontology, as shown in Figure 2.

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From a technical point of view, ontologies are commonly formalized in a specific language, OWL 2 (Web Ontology Language 2), which defines the logical relations among entities, and in the RDF Schema, a light and less expressive vocabulary to define classes, subclasses, and relations. Ontologies can be easily created with Prot\u00e9g\u00e9, an open-source program with a user-friendly interface to create entities and relations and options for saving them in OWL.

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\"Figure
Figure 2. Demonstrative example of an ontology (in orange) describing the classes or entities and their properties or relations in a domain of knowledge, also called \"T-Box\", and the individuals or instances represented according to the ontology (in yellow), also called \"A-Box\". As the ontology states that Paintings can depict (relation \"depicts\") an Iconography, we can reuse this pattern to express that the individual painting \"La Primavera\" by Botticelli depicts the three graces, another individual having as type the entity Iconography. Relations must be stated in the ontology to be used in data, and must respect the direction of the arrow. For example, when applying this ontology, we can't say that an iconography depicts an artwork \u2013 it should always be the contrary. Figure by Sofia Baroncini
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Several languages and applications exist. One of the most common areas of application in the DH sector is in the Semantic Web. Semantic Web is an extension of the hypertext web in which not only web pages, but also concepts are related to each other. URIs are used not only to identify web pages, but also to identify concepts, entities, and relationships. For example, this URI on Wikidata identifies the Mona Lisa painting, and it also states, through the URI indicating the relationship of \"creator\", that it was painted by Leonardo da Vinci, associated with another URI.

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The benefits of the Semantic Web and ontologies in general are multiple. They help algorithms to clearly identify concepts and differentiate among them, even if they have the same name (e.g., \"Venus\" as a planet is different from \"Venus\" indicating the deity of love in Greek mythology). As computers can process this information, computational operations are done with semantic data. An example is protein prediction in the field of biology, done through ontologies and Machine Learning.

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In the humanities area, ontologies are mainly used as standards to guarantee interoperability between datasets maintained by different institutions in the GLAM (Galleries, Libraries, Archives, Museums) sector. If structured data is described according to the same ontology, data can be integrated and queried together, even though separate datasets are created and maintained by different institutions. In this way, a global, interconnected knowledge graph can be created in a decentralized way. The use of ontologies to describe data is an important component of the creation of Linked (Open) Data, i.e., a network of integrated data described using common, open ontologies. The linked data cloud describes the massive, growing amount of LOD datasets and their interconnections (Figure 3).

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Following these principles, portals offering access to massive amounts of data were created, such as Europeana, the European portal for Cultural Heritage, or Artresearch.net, a knowledge graph integrating data from the art photographic archives of the PHAROS association.

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\"Figure
Figure 3. Snapshot of the Linked Data Cloud on 02/09/2026. Source: https://lod-cloud.net/
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Ontology Modeling

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But how to create an ontology? In this blog post, we will take you through an overview of the steps to create an ontology through the concrete example of the development of the Cultural Heritage Interactions Ontology (CHint) (Baroncini & Heuvel, 2026). The aim of the ontology is to represent various types of interactions between material and immaterial cultural heritage (CH) that occur over time and space. In other words, it relates a CH object with 1) ideas and values that are relevant in the context(s) in which the object is located (i.e., a belief system), 2) the function(s) that such objects acquire in different contexts, 3) the evolution of these features over time, 4) their interaction with contextual ephemeral events and immaterial cultural heritage practices, and 5) different aspects of uncertainty related to the reconstruction of past state-of-affairs of the object.

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Before getting into details, it is important to underline that there's never a single way to model knowledge. Every model reduces infinite reality by selecting specific features. For example, the floor plan of a building does not render the 3D appearance of the building, nor does a 3D accurate scan record the temperature inside the rooms. Every model follows a specific purpose or research question, and discards a certain amount of information.

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The same happens with data modeling. Whereas \"data\" \u2013 literally, something \"given\" from the Latin word datum – is perceived as being something neutral, it always reflects a particular point of view on reality. This is particularly evident when we deal with humanities data. Not only do the branches of study reflect a worldview or way of thinking, but also the information modeled relies on often uncertain, approximate, and incomplete sources, which raise a range of subjective interpretations about the past state of affairs.

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Several methodologies can be used to develop an ontology. Among them, agile and iterative approaches, such as NeOn (Su\u00e1rez-Figueroa et al., 2015), eXtreme Design (Presutti et al., 2009), and SAMOD, are particularly relevant. Instead of modeling the whole ontology at once, the developer divides the domain into smaller areas and adds them iteratively to the main ontology. During the development of CHint, we adopted the SAMOD method (Peroni, 2016) for modular development, with the aid of the Ontology Requirements Specification Document for the initial definition of the characteristics of the overall ontology (Su\u00e1rez-Figueroa et al., 2009). For this reason, we will focus on them in the illustration of the development process.

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Define the requirements

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In the first place, the scope and aim of the project should be defined: what's the aim of the modeling? In which domain? For whom? What questions should the model be able to answer? If a domain expert and a developer are involved, these aspects should be defined together. It is a fundamental phase, as the decisions that are taken in this step shape all the following process.

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The set of needs that the model should fulfill to be considered finished is called \"requirements\". Documents such as the Ontology Requirements Specification Document (Su\u00e1rez-Figueroa et al., 2009) are useful for clarifying these characteristics. In SAMOD, however, these requirements are progressively defined and refined through a series of concrete motivating scenarios. Rather than trying to specify the whole ontology from the beginning, each iteration focuses on a specific part of the domain. Following the SAMOD method, domain experts describe a specific motivating scenario, i.e., a small, concrete description of a problem in the domain that needs to be modeled, accompanied by examples. From this scenario, the developing team formulates informal competency questions, namely, questions that the ontology should eventually be able to answer (for example, \"which subjects are represented in Botticelli's Primavera\"?).

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For the development of the Cultural Heritage Interactions Ontology, it was set that the ontology aimed to narrow the gap between records about physical cultural heritage objects (e.g., paintings, altarpieces) and manifestations of immaterial culture (e.g., a certain belief, religious events) that regard them over time and space. Such interaction can indeed deeply change the object, resulting in new functions or iconography \u2013 take into account, for example, the religious objects often musealized, appreciated more for their aesthetic value than for their religious function after their decontextualization. The scope of application is the CH sector, and it is intended to be used by digital cultural historians and/or computer scientists interested in developing applications concerning cross-cultural understanding of CH objects. The intended use of the ontology is to \"express in a machine-readable format the complex interactions between contemporary culture and immaterial events, and thoughts that eventually influenced CH objects themselves, their function and/or meaning\" (Baroncini & Heuvel, 2026, p. 14). The technical requirements were an extensive reuse of available ontologies and the formalization in OWL 2. Whereas the document was initially used to set the aim, scope, and use of the ontology, further sections were filled during the following development steps. For example, the definition of the glossary of terms, i.e., keywords relevant to the domain, depended on the theories taken into account for the definition of the domain, illustrated in the following section. Another example is the definition of competency questions, defined in the SAMOD iterations during the development. Furthermore, at this initial stage, we identified a set of requirements the ontology should address, developed in specific scenarios during\u00a0the development steps.

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From ideas to sketches: top-down and bottom-up approaches

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Figure 4. Sketches by Sofia Baroncini and Charles van den Heuvel to grasp the interaction between artworks and immaterial culture over time and space at the beginning of the development of the CHint Ontology. Copyright of the authors.
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The first important step to take is to think deeply about the domain. Depending on the cases and theories available, two main approaches (or a mix of them) are possible. The first one, top-down, consists of searching for pre-existing domain theories that model the domain and implementing them in the modeling. In this case, the developer adopts a deductive approach, and they move from the theory to the implementation. The second, opposite approach is to induce a general structure from multiple real cases, called bottom-up. For example, if there is a dataset about artworks sold in auctions, we can infer how artworks interact with the auction events and buyers from the data itself, and base the ontology on that rich example.

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In the DH domain, ontologies often rely on preexisting theories or modeling patterns to represent the domain at hand. Indeed, domain theories are already a conceptualization of the world proposed by historians, philosophers, and humanists who are or were experts in their fields. For this reason, domain theories can be an invaluable source when formalizing information. Nevertheless, theories may have their limits, as they were not at first created to be a computational model, and they reflect a socioculturally situated worldview, which may be outdated, biased, or limited to a certain culture (e.g., the Western world).

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Once the best approach has been identified, according to the available theories or data, it is a good idea to start sketching on a whiteboard or piece of paper how concepts relate to each other. Figure 4 shows the results of a first brainstorming session we had to create the CHint ontology, in which we thought about how the chosen theories could relate to each other. For the development, we have adopted a top-down approach, as we identified relevant theories concerning the evolution of time and space, frames, and the relation of works of art with a belief system.

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The importance of standards

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It is good practice to reuse existing models if they are in line with the aims of the ontology. As one of the main goals of the Semantic Web and Linked Open Data is the integration of different datasets described with a common structure, it is fundamental to identify which standards and existing ontologies can be reused for the task. Usually, standards for each domain exist, providing a backbone of how the concepts are organized in the domain. For the CH domain, the main standard is CIDOC-CRM, a conceptual framework developed and maintained by the International Council of Museums (ICOM), which serves as a structure to model museum data in different areas, from art to maritime CH. It is a good practice to reuse the standards and existing ontologies as much as possible, as they have already solved core modeling issues, making the work of the ontology developer easier and guaranteeing interoperability.

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In the CHint development, this means that existing models such as CIDOC-CRM can provide concepts that are relevant to the domain. Reusing these solutions improves interoperability and makes the resulting ontology easier to connect with other datasets.

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Draft. Test. Iterate

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Once there is an idea of the domain, scope, data, and theories available, the actual modeling can start. As cited above, many methodologies focus on the development of small portions of the ontology. Each iteration should include at least two types of testing: 1) testing the logical consistency of the ontology through a reasoner, and 2) testing the model against real data (A-BOX). This ensures that there are no logical inconsistencies and that the ontology can actually address the real-world scenario taken into account.

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Figure 5. Overview of the ontology development process according to SAMOD. Source: Peroni, S. (2016). https://doi.org/10.6084/M9.FIGSHARE.3189769. Licensed under CC BY 4.0
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Draft

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As introduced above, the SAMOD method1 divides the ontology into small motivating scenarios to allow agile development and focus on simpler aspects (Figure 5). Each scenario is a textual description of the area of the domain, and it is accompanied by a glossary of terms describing the core terminology of the scenario.

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For the development, we've taken into account a specific case study, chosen for its richness, as a concrete example on which the model should be tested, constituting the A-BOX of the ontology. The case concerns the relics of\u00a0 St. Servatius preserved in Maastricht, the Netherlands, which are regularly brought in procession from the 14th century to the present day. For the richness of documentation, the strong relation with the Catholic community, and the frequency with which it interacts with an immaterial cultural manifestation, it was considered a prime example for the development.

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The module Historical Frame of the CHint ontology was developed in one iteration and had one motivating scenario.

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We quote here, as a way of example, one part of the motivating scenario:

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A CH object has one or multiple contexts that are related to it. A context expresses the historical, socio-cultural situation in which an artwork exists. By definition, its delimitation is fuzzy, as it corresponds to a certain culture. It includes several traits of various natures, such as religion, social practice, taste, style, etc. Humans, and experts in art history, history, and so on, identify sets of salient traits for each context. In doing so, they frame reality in the sense of Nelson's theory to abstract such traits. In other words, they create observation frames that isolate from the reality contexts that present unifying traits. In doing so, they create a Historical Frame, which is a portion of the spacetime continuum created to better observe a context that already presents traits of unity. The traits are then collected in Reference Frames, defined according to Minsky's theory, that work as the domain pre-knowledge which is necessary for relating CH objects to their contexts (e.g., placing Raffaello's work in the Italian Renaissance).

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An object participates in one or more cultural frames, corresponding to 1) the context of artwork creation, and 2) further contexts the object traverses.

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The scenario, indeed, describes the interaction of CH objects with the socio-cultural, immaterial contexts in which they existed \u2013 either at the time of their creation, or in following situations. The glossary included key terms such as historical frame, time, event, etc.

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For this scenario, we defined Competency Questions (CQs), questions that data described with the ontology should be able to answer. For this reason, the CQs explicitly refer to the case study:

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On the basis of the motivating scenario, glossary, and CQs, the ontology engineer drafts a modelet representing how the concepts relate to each other. The design is first a sketch, which is then rendered in an OWL 2 ontology through programs for ontology editing such as Prot\u00e9g\u00e9. In this stage, the design should take into account existing standards and available modeling patterns, but without explicitly importing them. Figure 6 illustrates the modelet of the Historical Frame motivating scenario illustrated with the Graffoo representation through the program draw.io. Whereas not explicitly introduced in the modelet to lower the complexity of the task at this step, classes and relations of existing ontologies, mainly standards, were taken into account. For example, the class E92 Spacetime-Volume of CIDOC-CRM was already identified as being in line with the concept of historical frame, as it describes a portion of space and time, or the Cultural Phenomenon class of the ICON ontology, representing deep socio-cultural phenomena recognized in artworks.

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Figure 6. Modelet of the Historical Frame module of the CHint ontology. Created by Sofia Baroncini. Available at Zenodo (DOI: 10.5281/zenodo.20393679). Licensed under CC BY 4.0
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Test, iterate, and align

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After the creation of the modelet, its logical consistency should be tested through a reasoner, an operation that can be done in Prot\u00e9g\u00e9. If the test doesn't raise any error, then a small dataset of real examples described according to the model (A-BOX) needs to be created, and the logical test repeated. If no errors are raised, the Competency Questions should be translated into real SPARQL queries and performed over the dataset. If the queries give the expected result, we can merge the modelet with the main ontology developed in the previous phases.

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The last phase of each iteration is the refactoring, namely, the alignment of the current ontology with existing ones, or replacing classes and relations with equivalent or more appropriate terms from existing models. For example, during the modeling of the modelet, we previously identified the class E92 Spacetime-Volume of CIDOC-CRM as suitable to express the concept of Historical Frame, of which it could be a specification. At this stage, we make this alignment explicit, and we declare the class Historical Frame as a subclass of crm:E92. All the tests should be performed again.

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Figure 7. Aligned, final ontological representation of the Historical Frame module. Created by Sofia Baroncini. Available at Zenodo (DOI: 10.5281/zenodo.20393679). Licensed under CC BY 4.0
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The process should be iterated on all the scenarios until there are no more scenarios to be modeled. At that point, the ontology is ready to be published.

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Publishing and making the ontology FAIR

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After the ontology is developed, it is still important to make it FAIR (Findable, Accessible, Interoperable, Reusable). It is good practice to assign it a permanent URI, publish documentation, and include it in the main indexes of LOD vocabularies.

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A permanent URI can be assigned through w3id.org, whereas various tools, such as PyLode, can be used to automatically generate the documentation of the ontology from the OWL 2 file.

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In the case of CHint, a permanent ID was assigned to the ontology OWL file,\u00a0 the development and documentation, which was\u00a0created through PyLode.

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Finally, it is highly recommended to use tools such as the Ontology Pitfalls Scanner (OOPS!) and FAIR Ontology Pitfalls Scanner (FOOPS!) to detect errors or missing descriptions (e.g., labels, inverse relations) and fix the ontology accordingly before publishing it.

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Following these steps, it is possible to create a robust ontology, which can address specific domain aspects and be aligned with standards.

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References

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Baroncini, S., & van den Heuvel, C. (2026). The Historical Framing Problem: Temporal Modeling of Interactions between Tangible and Intangible Cultural Heritage. Semantic Web, 17(4), 1\u201343. https://doi.org/10.1177/22104968261454485

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Peroni, S. (2016). SAMOD: An agile methodology for the development of ontologies. Proceedings of the 13th OWL: Experiences and Directions Workshop and 5th OWL Reasoner Evaluation Workshop (OWLED-ORE 2016). https://doi.org/10.6084/M9.FIGSHARE.3189769

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Presutti, V., Daga, E., Gangemi, A., & Blomqvist, E. (2009). eXtreme Design with Content Ontology Design Patterns. Proceedings of the 2009 International Conference on Ontology Patterns, 516, 83\u201397. https://ceur-ws.org/Vol-516/pap21.pdf

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Su\u00e1rez-Figueroa, M. C., G\u00f3mez-P\u00e9rez, A., & Fern\u00e1ndez-L\u00f3pez, M. (2015). The NeOn Methodology framework: A scenario-based methodology for ontology development. Applied Ontology, 10(2), 107\u2013145. https://doi.org/10.3233/AO-150145

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Su\u00e1rez-Figueroa, M., Gomez-Perez, A., & Villazon Terrazas, B. (2009). How to Write and Use the Ontology Requirements Specification Document. On the Move to Meaningful Internet Systems: OTM 2009: Confederated International Conferences, CoopIS, DOA, IS, and ODBASE 2009, Vilamoura, Portugal, November 1-6, 2009, Proceedings, 2, 966\u2013982. https://doi.org/10.1007/978-3-642-05151-7_16

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Featured image: Sketches by Sofia Baroncini and Charles van den Heuvel to grasp the interaction between artworks and immaterial culture over time and space at the beginning of the development of the CHint Ontology. Copyright of the authors.

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  1. This blog post provides just a general overview of the process to make the methodology more accessible and understandable. For a complete and detailed overview of the modeling process, refer to Peroni (2016). [↩]
    2. \n
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Jente Houweling published her first PhD thesis chapter earlier this year:\n\"ToxTempAssistant: using large language models to standardise cell-based toxicological test method descriptions\"\n(doi:10.1080/2833373X.2026.2638036). So far, I have been blogging about\nmany of the articles on which I am (co-)author. To put it in context. To reflect on the work. I have been postponing\nwriting about this paper because there is a lot to reflect on. I will pick out two things. First, I look at the use\nof AI. The second is the unique, innovatie publishing model of the journal where the article was published.\nIf you want to just see it in action, ToxTempAssistant is running\non the Virtual Human Platform for safety assessment.

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Before we go there, just a quick note on what ToxTemps are and ToxTempAssistent actually is:

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The ToxTemp template, based on OECD Guidance Document 211, standardises reporting for cell-based NAMs. However,\ncompleting its 77 questions constitutes a substantial bottleneck. The aim of this study is to introduce ToxTempAssistant,\na Large Language Model (LLM)-assisted web tool that supports toxicologists in drafting ToxTemp documents based on\nuser-supplied context documents. This study quantifies the tool's baseline performance under controlled conditions.\nToxTempAssistant uses grounded, per-question prompting with mandatory source attribution.

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The LLM aspects

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AI is very old. Arguably, my PhD thesis\nhad this as key topic, though I prefered to use to term chemometric or machine learning.\nCritial thinking has been essential to this field for a long time, and much of the PhD thesis is actually\nabout critically assessing the performance of the methods used in the thesis. There is decades of research\nhow you do this. Sadly, when it comes to Large Language Models (LLMs), these are not routinely used.

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LLMs are indeed something new. I have seen natural language processing\nresearch when I was Cambridge with Peter Murray-Rust. The current LLMs are different, less deterministic, more probabilistic.\nFrom a chemometrics perspective, that makes sense. Language is complex, and not so deterministic in itself. Moreover,\nwhen representing words, sentences as numbers, you can integrate any resource (think data tables, images, etc). Even more,\ndigital representation was even more the central theme of my PhD thesis.

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But because of the nature of the method, the nature of how the commercial, better known models are trained (and the\nimpact on the notion of copyright), the impact on the climate emergency,\nthe black box that these LLMs often are, there are so many technical, scientific, and ethical reasons to stay away from them.

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You can write books about that. Literally (I did not read them yet):

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(I have the feeling I am missing one title I wanted to highlight. If I remember, I will add it.)

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And more here and here.\nAnd I am looking forward to reading Deep Unlearning: The Rise of AI and the Radicalization of a Tech Idealist.\nAlso, I recommend at least following Timnit Gebru and\nEmily Bender.

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A year ago, I signed the Open Letter: Stop the Uncritical Adoption of AI Technologies in Academia,\nnow signed by more than 2,000 people (it is not too late).

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So, with all these things mind, I am happy that Jente did critically adopt LLMs in her work. The paper includes\nvarious experiments to explore the impact of various model parameters on generating nonsense. She also explored\nto use of alternative LLMs platforms, opening the option that some day it runs on other, more ethical platforms.\nToxTempAssistant, moreover, limits the material it takes information from, from a limited set of sources, provided\nby the users. Of course, the model itself is still training on resources with questionable provenance.

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Jente's paper describes the use of positive and negative controls to put the performance in perspective.\nIn doing so, the paper formalizes how to evaluate the use of LLMs in situations where the LLM is used\nto summarize other reports, a common thing to do. This allows us to monitor the impact of, for example,\nnew LLM releases.

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The results are promising and various independent projects have shown interest in adoption. The ToxTemp\nreports are important for safety assessment: they provide essential context to experimental results and\nas such essential to the FAIR-ness of toxicology data.

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Open Peer Review

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The ToxTempAssistant paper is published in the relatively new journal Evidence-Based Toxicology (EBT):

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Evidence-Based Toxicology is a broad-focus, gold open-access journal, created to support the use of open science practices and\nevidence-based methods in toxicology and environmental health.

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So, CC-BY license (gold open access) and support for Open Science. And Open Peer Review, as we will see. Also,\nI undestand it is not a diamond open access journal, so expect APCs.

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The journal has a community on Zenodo for preprints and peer-reviews.\nI think this is a really nice choice. Of course, a journal specific preprint server has downsides too. For example,\nif it gets rejected from EBT, do you use the EBT preprint server when submitting to another journal? Do you upload\na new version (after all, you should address some of the comments why it was rejected) to another preprint server?

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The EBT preprint gets a record and revisions are uploaded as new versions to the same Zenodo record\n(doi10.5281/zenodo.17192970):

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But because EBT uses open peer review, there is a parallel Zenodo entry with the reviews\n(doi10.5281/zenodo.17278785):

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The last version here is the acceptance notice:

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One of the reviewer suggestions was to use the TRIPOD-LLM template\n(doi:10.1038/s41591-024-03425-5), which was included in a\nlater revision. That made a lot of sense and is a nice example how the journal actively works\non applying open science ideas. The journal webpage writes:

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We define \"open science\" as the set of practices aimed at improving the transparency, validity,\nreproducibility, and accessibility of scientific research, while promoting equality of\nopportunity to participate in and benefit from the products of said research.

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One comment here is that the template asks on what page that point of the checklist is discussed\nin the article. That is nice, but links it directly to the revision of the manuscript that\nform applies too, but that is not reported in the template. Not ideal. Then again, the point\nis the checking, so maybe not a big deal.

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Another comment is that it seems the journal website's page for the article does not seem to actually\nlink to the preprints nor the peer-review reports (or acceptance note). So, in time, these\nopen science aspects of this article will likely get lost in time. Who will find those reports\nif the article does not cite them? This will require Taylor&Francis to modernize the publishing\nmodel, and I sincerly doubt that that will ever happen.

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Prof. Anne Kienhuis, one of the co-authors, suggested\nthis journal lead by Prof. Paul Whaley.\nAnd I am happy to have seen this new approach in action and like to thank Paul for pushing for\nthese innovations. I recommend trying it yourself for your next toxicology work.

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References

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Gallifant, J., Afshar, M., Ameen, S., Aphinyanaphongs, Y., Chen, S., Cacciamani, G., Demner-Fushman, D., Dligach, D., Daneshjou, R., Fernandes, C., Hansen, L. H., Landman, A., Lehmann, L., McCoy, L. G., Miller, T., Moreno, A., Munch, N., Restrepo, D., Savova, G., \u2026 Bitterman, D. S. (2025). The TRIPOD-LLM reporting guideline for studies using large language models. Nature Medicine, 31(1), 60\u201369. https://doi.org/10.1038/s41591-024-03425-5 [cito:discusses] CrossRef Scholia
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Houweling, J. (Johanne) M., Arras, M. M., Willighagen, E., Kienhuis, A., Jennen, D., & Evelo, C. (2026). ToxTempAssistant: Using Large Language Models to Standardise Cell-Based Toxicity Test Method Descriptions. Zenodo. https://doi.org/10.5281/ZENODO.17192970 [cito:citesAsEvidence] CrossRef Scholia
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Houweling, J. M., Arras, M. M. L., Willighagen, E. L., Jennen, D. G. J., Evelo, C. T., & Kienhuis, A. S. (2026). ToxTempAssistant\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u202f: using large language models to standardise cell-based toxicological test method descriptions. Evidence-Based Toxicology, 4(1). https://doi.org/10.1080/2833373x.2026.2638036 [cito:discusses] CrossRef Scholia
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Krebs, A., Waldmann, T., Wilks, M. F., van Vugt-Lussenburg, B. M. A., van der Burg, B., Terron, A., Steger-Hartmann, T., Ruegg, J., Rovida, C., Pedersen, E., Pallocca, G., Luijten, M., Leite, S. B., Kustermann, S., Kamp, H., Hoeng, J., Hewitt, P., Herzler, M., Hengstler, J. G., \u2026 Leist, M. (2019). https://www.altex.org/index.php/altex/article/view/1339. ALTEX, 682\u2013699. https://doi.org/10.14573/altex.1909271 [cito:citesForInformation] CrossRef Scholia
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Whaley, P. (2026). Evaluation Reports for TEBT-2025-0014 | Houweling et al. Zenodo. https://doi.org/10.5281/ZENODO.17278785 [cito:citesAsEvidence] CrossRef Scholia
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","doi":"https://doi.org/10.59350/v5ehk-42y77","guid":"https://doi.org/10.59350/v5ehk-42y77","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790985600,"reference":[{"id":"https://doi.org/10.1080/2833373x.2026.2638036","unstructured":"Houweling, J. M., Arras, M. M. L., Willighagen, E. L., Jennen, D. G. J., Evelo, C. T., & Kienhuis, A. S. (2026). ToxTempAssistant : using large language models to standardise cell-based toxicological test method descriptions. Evidence-Based Toxicology, 4(1). [cito:discusses]"},{"id":"https://doi.org/10.14573/altex.1909271","unstructured":"Krebs, A., Waldmann, T., Wilks, M. F., van Vugt-Lussenburg, B. M. A., van der Burg, B., Terron, A., Steger-Hartmann, T., Ruegg, J., Rovida, C., Pedersen, E., Pallocca, G., Luijten, M., Leite, S. B., Kustermann, S., Kamp, H., Hoeng, J., Hewitt, P., Herzler, M., Hengstler, J. G., \u2026 Leist, M. (2019). https://www.altex.org/index.php/altex/article/view/1339. ALTEX, 682\u2013699. [cito:citesForInformation]"},{"id":"https://doi.org/10.5281/zenodo.17278785","unstructured":"Whaley, P. (2026). Evaluation Reports for TEBT-2025-0014 | Houweling et al.. Zenodo. [cito:citesAsEvidence]"},{"id":"https://doi.org/10.5281/zenodo.17192970","unstructured":"Houweling, J. (Johanne) M., Arras, M. M., Willighagen, E., Kienhuis, A., Jennen, D., Evelo, C., Arras, M. M., Jennen, D., Willighagen, E., Evelo, C., & Kienhuis, A. (2026). ToxTempAssistant: Using Large Language Models to Standardise Cell-Based Toxicity Test Method Descriptions. [cito:citesAsEvidence]"},{"id":"https://doi.org/10.1038/s41591-024-03425-5","unstructured":"Gallifant, J., Afshar, M., Ameen, S., Aphinyanaphongs, Y., Chen, S., Cacciamani, G., Demner-Fushman, D., Dligach, D., Daneshjou, R., Fernandes, C., Hansen, L. H., Landman, A., Lehmann, L., McCoy, L. G., Miller, T., Moreno, A., Munch, N., Restrepo, D., Savova, G., \u2026 Bitterman, D. S. (2025). The TRIPOD-LLM reporting guideline for studies using large language models. Nature Medicine, 31(1), 60\u201369. [cito:discusses]"}],"rid":"pn95g-v4h02","summary":"Jente Houweling published her first PhD thesis chapter earlier this year: \"ToxTempAssistant: using large language models to standardise cell-based toxicological test method descriptions\" (doi:10.1080/2833373X.2026.2638036). So far, I have been blogging about many of the articles on which I am (co-)author. To put it in context. To reflect on the work.","tags":["Fair","Llm","Vhp4safety","Openscience"],"title":"New paper: \"ToxTempAssistant: using large language models to standardise cell-based toxicological test method descriptions\"","updated_at":1791016505,"url":"https://chem-bla-ics.linkedchemistry.info/2026/10/03/new-paper-toxtempassistant-using-large-language-models-to-standardise-cell-based-toxicological-test-method-descriptions.html","version":"v1"},{"authors":[{"affiliation":[{"name":"Imperial College London, Chemstry"}],"contributor_roles":[],"family":"Rzepa","given":"Henry","url":"https://orcid.org/0000-0002-8635-8390"}],"blog":{"authors":[{"name":"Henry Rzepa","url":"https://orcid.org/0000-0002-8635-8390"}],"community_id":"8fb94c86-e95f-41cf-aac2-a2877ffc1b5f","created":1693094400,"current_feed_url":null,"description":"Chemistry with a twist","doi":"https://doi.org/10.59350/rzepa","favicon":"https://rogue-scholar.org/api/communities/8fb94c86-e95f-41cf-aac2-a2877ffc1b5f/logo","feed_format":"application/atom+xml","feed_url":"https://www.ch.ic.ac.uk/rzepa/blog/?feed=atom","filter":null,"generator":"WordPress","home_page_url":"https://www.ch.ic.ac.uk/rzepa/blog","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"rzepa","status":"active","subfield":"1606","title":"Henry Rzepa's Blog","updated":1791013525,"use_api":true},"blog_name":"Henry Rzepa's Blog","blog_slug":"rzepa","content_html":"
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Metalla-aromatics have been defined as metallacycles that are derived from the formal replacement of a carbon atom in the framework of an organic aromatic ring with a metal fragment.[1]. Here I explore whether this simple definition can be broadened to sulfur-nitrogen rings which contain few[2],[3] if indeed any[4],[5],[6],[7] carbon atoms and which also happen to be planar aromatic molecules.

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Prologue

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Our story starts with the authors of this article[8] reporting the formation of the sulfur-nitrogen titanacycles 1[9] and 2[10] (green in the scheme 1 below) from Cp2Ti(CO)2 reacting with S4N4. Isolating compound 2 was something of a surprise, since they had been expecting/hoping to get 3[11] instead (red in scheme 3 below). This result was unexplained in the article and unremarked upon by anyone else since.

\n

\"\"
\nScheme 1. Formed products 1 – 2\u00a0from the reaction of Cp2Ti(CO)2 with S4N4.

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To develop the prologue, we start with compound 7 (Scheme 2) which was described[3] as a (H\u00fcckel-class) 10 \u03c0-aromatic ring (6e from double bonds, 4e from S lone pairs) containing one ring carbon atom and represented in the original paper as 7a. In fact, NBO7 analysis[12],[13]\u2021 (as obtained with no 3-centre bonds allowed) suggests that 7b is a more accurate representation (4e from two \u03c0-double bonds and 6e from lone pairs = 10\u03c0 =4n+2, n=2 ). Molecule 7b\u00a0has a computed NICS(0) (= Nucleus Independent Chemical Shift at ring centroid) value of -9.6 ppm,[14] NICS here being used as an approximate indicator of aromaticity\u00a0(or lack of it),\u00a0with e.g. the archetypal 4n+2 (n=1) \u03c0-aromatic benzene giving a NICS(0) value of ~-10. For 4n/4n+2 aromaticity selection rules, see e.g. [15],[16]
\n\"\"
\nScheme 2. Compounds 7a/b\u00a0and 7c.

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A replacement of the carbon and its attached ester group according to the definition above by using (Cp.CO)Ti as a transition metal results in e.g. 7c – a compound not dissimilar to the compound discussed in the previous post[17]. A MN15L/Def2-TZVPP calculation[18] gives the geometry shown in Figure 1. A NBO7[12] localisation procedure\u2021 gives the result[19] shown as 7c (Scheme 2, Figure 2), with back bonding into titanium d-orbitals and the three \u03c0-bonds and two lone pairs (one N, one S) resulting in a total of ten cyclically conjugated \u03c0-electrons.

\n

\"\"
\nFigure 1. Calculated\u00a0MN15L/Def2-TZVPP/SCRF=DCM structure of compound 7c.

\n

\"\"

\n

Figure 2. Five NBO7 localised orbitals representing 7c.

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A NICS(0) NMR estimate of the aromaticity for 7c gives an antiaromatic value of +9.8 ppm,[20], and\u00a0hence tending to M\u00f6bius antiaromaticity according to the selection rules for 4n+2 (n=2) electrons.[15],[16] This combination of 4n+2 (n=2) conjugated \u03c0-electrons and NMR-based antiaromaticity allows one to infer that there must be one orbital phase shift in the conjugated \u03c0-electrons, presumably at either the Ti=S centre or the Ti=N centre but not both. This pair of calculations provides an interesting and useful prologue to and calibration of the NICS(0) procedure as an (anti)aromaticity metric in such systems.

\n

Discussion. Molecule 1.

\n

CASZOL10 (molecule 1, scheme 1, Figure 3), has an NBO7\u2021 Lewis localised structure[21]\u00a0shown as 1a rather than the literature representation 1[8] (Scheme 1, Figure 4). As with 7c, it comprises three \u03c0-bonds and two lone pairs (one N, one S). In contrast to 7c, the NICS(0) = -6.7[22] suggests moderate aromatic character, which as a 10 \u03c0-electron aromatic must have either no phase shifts or two. It suggests that, as informed by 7c, the Ti=N bond does not contribute any phase shifts. On the basis of these results, we suggest that molecule 1 can be described as a H\u00fcckel type (4n+2) moderately aromatic inorganic metallacycle.

\n

\"\"
\nFigure 3. Calculated structure of 1, CASZOL10. The purple point is the NICS probe.

\n

\"\"
\nFigure 4. Five NBO7 localised orbitals representing 1a (total NBO7 orbital occupancy 8.39e)

\n

Discussion. Molecule 2.

\n

Molecule 2 (CIWFIX10, Figure 5) has NICS(0) = -6.0 ppm[23] for 8\u03c0 electrons (one NBO7 double bond and three NBO7 lone pairs[24]) represented as 2a in scheme 1 (Figure 5).

\n

\"\"
\nFigure 5. Structure of 2,\u00a0CIWFIX10. The purple point is the NICS atom.

\n

\"\"

\n

Figure 6. Four NBO7 localised orbitals representing 2b (total NBO orbital occupancy 6.92e).

\n

The moderate NMR-based aromaticity for a 4n (n=2) electron cycle implies M\u00f6bius character, [15],[16] whereby significant twisting of the adjacent sulfur-nitrogen ring orbitals allows a phase shift to occur via an unoccupied Ti d-orbital (Figure 7).

\n

\"\"
\n

\n

Discussion. Unformed Compounds (Scheme3).

\n

\"\"

\n

Scheme\u00a03. Unformed compounds 3–6 from the reaction shown in Scheme 1.

\n

Compounds 3-6 are all computed as higher in free energy than 2. Compound 3a (mysteriously not formed in the original report[8]) is +13.7 kcal/mol higher than 2, and clearly non-aromatic (NICS(0) = -0.29 ppm). \u00a0This may be because the ring is relatively flat and not capable of the twisting required to become M\u00f6bius aromatic, something that was possible in 2.[25],[26],[27] Compound 4 (orange in scheme) is interesting since it is only 3.9 kcal/mol higher than 2 and having 8\u03c0 electrons (two bonds, two lone pairs) has a NICS(0) of -8.4 ppm[28] appropriate for a M\u00f6bius metallaaromatic and again has a ring capable of the required twisting as per 2. It might be synthesizable if formed by a different method.

\n

Conclusions

\n

Both 1 and 2 are suggested here as examples of inorganic metallaaromatics, respectively of the H\u00fcckel and M\u00f6bius type,[15],[16] and uniquely with no carbon atoms present in the aromatic ring – a hitherto unrecognised class of aromatic molecule. We here argue that the non-formation of compound 3 as indicated in original article[8] is because it is non-metalla-aromatic, and in its place compound 2 is formed precisely because it IS likely to be metalla-aromatic. It is our expectation that many more such inorganic metalla-aromatics could exist.

\n
\n

\u2021Use of the older NBO3 procedure is deprecated here, since it is prone to converging for these types of systems to unphysical solutions. We have established that the essential character of the NBO7 orbitals does not depend on the quality of the basis set used[29] or the DFT procedure (albeit tested only for one additional functional, \u03c9B97XD[30],[31]).

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\n

This post has DOI: 10.59350/dsyea-mrq85

\n

References

\n
  1. D. Chen, Y. Hua, and H. Xia, \"Metallaaromatic Chemistry: History and Development\", Chemical Reviews, vol. 120, pp. 12994-13086, 2020. https://doi.org/10.1021/acs.chemrev.0c00392\n\n
    2. \n
  2. R. Jones, J.L. Morris, A.W. Potts, C.W. Rees, D.J. Rigg, H.S. Rzepa, and D.J. Williams, \"Electronic and crystallographic structures of trithiadiazepines\", Journal of the Chemical Society, Chemical Communications, pp. 398, 1985. https://doi.org/10.1039/c39850000398\n\n
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  3. S.T.A.K. Daley, C.W. Rees, and D.J. Williams, \"1,3,5,2,4-Trithiadiazepines and 1,3,5,2,4,6-trithiatriazepines, new 10? heteroaromatic systems\", Journal of the Chemical Society, Chemical Communications, pp. 55, 1984. https://doi.org/10.1039/c39840000055\n\n
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  4. P.N. Jagg, P.F. Kelly, H.S. Rzepa, D.J. Williams, J.D. Woollins, and W. Wylie, \"The preparation, X-ray crystal structure and theoretical study of [CoCp\n <sub>2</sub>\n ][S\n <sub>3</sub>\n N\n <sub>3</sub>\n ], (Cp = cyclopentadienyl), a novel stacking compound incorporating multiple C\u2013H \u22ef N(p\n <sub>\u03c0</sub>\n ) interactions\", J. Chem. Soc., Chem. Commun., vol. 0, pp. 942-944, 1991. https://doi.org/10.1039/c39910000942\n\n
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    6. \n
  6. J. Galan-Mascaros, A.M. Slawin, J. Derek Woollins, and D.J. Williams, \"\u03c0-facial interactions between Cl\u2212 and [S4N3]+. X-ray crystal structure of [S4N3]Cl\", Polyhedron, vol. 15, pp. 4603-4605, 1996. https://doi.org/10.1016/0277-5387(96)00223-9\n\n
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  7. T. Chivers, and R.S. Laitinen, \"Chalcogen\u2013Nitrogen Chemistry\", 2021. https://doi.org/10.1142/12397\n\n
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  8. C.G. Marcellus, R.T. Oakley, W.T. Pennington, and A.W. Cordes, \"Titanium sulfur nitrogen heterocycles: preparation and molecular structures of titanocene trisulfur tetranitride (.eta.5-C5H5)2TiS3N4 and titanocene trisulfur dinitride (.eta.5-C5H5)2TiS3N2\", Organometallics, vol. 5, pp. 1395-1400, 1986. https://doi.org/10.1021/om00138a016\n\n
    9. \n
  9. H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP G = -2649.576493\", 2026. https://doi.org/10.5281/zenodo.22195764\n\n
    10. \n
  10. H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67\", 2026. https://doi.org/10.5281/zenodo.22199646\n\n
    11. \n
  11. H. Rzepa, \"Cp2TiS3N2, MN15L/Def2-TZVPP G = -2540.173075\", 2026. https://doi.org/10.5281/zenodo.22193016\n\n
    12. \n
  12. E.D. Glendening, C.R. Landis, and F. Weinhold, \"<i>NBO 7.0</i>\n : New vistas in localized and delocalized chemical bonding theory\", Journal of Computational Chemistry, vol. 40, pp. 2234-2241, 2019. https://doi.org/10.1002/jcc.25873\n\n
    13. \n
  13. H. Rzepa, \"Reees 8 (MOs) NBO\", 2026. https://doi.org/10.5281/zenodo.22874369\n\n
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  14. H. Rzepa, \"Reees 8 (MOs) NMR Bq\", 2026. https://doi.org/10.5281/zenodo.22876817\n\n
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  15. H.S. Rzepa, \"M\u00f6bius Aromaticity and Delocalization\", Chemical Reviews, vol. 105, pp. 3697-3715, 2005. https://doi.org/10.1021/cr030092l\n\n
    16. \n
  16. P.L. Ayers, R.J. Boyd, P. Bultinck, M. Caffarel, R. Carb\u00f3-Dorca, M. Caus\u00e1, J. Cioslowski, J. Contreras-Garcia, D.L. Cooper, P. Coppens, C. Gatti, S. Grabowsky, P. Lazzeretti, P. Macchi, ?. Mart\u00edn Pend\u00e1s, P.L. Popelier, K. Ruedenberg, H. Rzepa, A. Savin, A. Sax, W.E. Schwarz, S. Shahbazian, B. Silvi, M. Sol\u00e0, and V. Tsirelson, \"Six questions on topology in theoretical chemistry\", Computational and Theoretical Chemistry, vol. 1053, pp. 2-16, 2015. https://doi.org/10.1016/j.comptc.2014.09.028\n\n
    17. \n
  17. H. Rzepa, \"Exploring the effect that causes ring-size specificity of transition metals for polysulfide dianions: Cyclopentadienyl-2,6-di-isopropylphenoxy Titanium pentasulfide.\", 2026. https://doi.org/10.59350/6hj5w-5w040\n\n
    18. \n
  18. H. Rzepa, \"CpCOTiS3N3 (from Rees system)\", 2026. https://doi.org/10.5281/zenodo.22869370\n\n
    19. \n
  19. H. Rzepa, \"CpCOTiS3N3 (from Rees system) Compound 7c NBO7\", 2026. https://doi.org/10.5281/zenodo.23061061\n\n
    20. \n
  20. H. Rzepa, \"CpCOTiS3N3 (from Rees system) NMR Bq Isotropic = -9.8464\", 2026. https://doi.org/10.5281/zenodo.22869771\n\n
    21. \n
  21. H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP Compound 1b, G = -2649.576493 NBO7\", 2026. https://doi.org/10.5281/zenodo.22934627\n\n
    22. \n
  22. H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP G = -2649.576493 NMR Bq Isotropic = 6.6460\", 2026. https://doi.org/10.5281/zenodo.22232235\n\n
    23. \n
  23. H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67 NMR Bq Isotropic = 6.0085\", 2026. https://doi.org/10.5281/zenodo.22225961\n\n
    24. \n
  24. H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67 Compound 2 NBO7\", 2026. https://doi.org/10.5281/zenodo.23018389\n\n
    25. \n
  25. H.S. Rzepa, \"A Double-Twist M\u00f6bius-Aromatic Conformation of [14]Annulene\", Organic Letters, vol. 7, pp. 4637-4639, 2005. https://doi.org/10.1021/ol0518333\n\n
    26. \n
  26. H.S. Rzepa, \"Lemniscular Hexaphyrins as Examples of Aromatic and Antiaromatic Double-Twist M\u00f6bius Molecules\", Organic Letters, vol. 10, pp. 949-952, 2008. https://doi.org/10.1021/ol703129z\n\n
    27. \n
  27. S.M. Rappaport, and H.S. Rzepa, \"Intrinsically Chiral Aromaticity. Rules Incorporating Linking Number, Twist, and Writhe for Higher-Twist M\u00f6bius Annulenes\", Journal of the American Chemical Society, vol. 130, pp. 7613-7619, 2008. https://doi.org/10.1021/ja710438j\n\n
    28. \n
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    29. \n
  29. H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-QZVPP Compound 1b, G = -2649.576493 NBO (not 7)\", 2026. https://doi.org/10.5281/zenodo.22933586\n\n
    30. \n
  30. H. Rzepa, \"Cp2TiS3N4, wB97XD/Def2-TZVPP Compound 1b, G = -2649.576493 NBO (not 7)\", 2026. https://doi.org/10.5281/zenodo.23034010\n\n
    31. \n
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    32. \n
\n\n
","doi":"https://doi.org/10.59350/dsyea-mrq85","guid":"https://www.ch.ic.ac.uk/rzepa/blog/?p=32123","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790985600,"reference":[{"id":"https://doi.org/10.1021/acs.chemrev.0c00392","unstructured":"D. Chen, Y. Hua, and H. Xia, \"Metallaaromatic Chemistry: History and Development\", Chemical Reviews, vol. 120, pp. 12994-13086, 2020."},{"id":"https://doi.org/10.1039/c39850000398","unstructured":"R. Jones, J.L. Morris, A.W. Potts, C.W. Rees, D.J. Rigg, H.S. Rzepa, and D.J. Williams, \"Electronic and crystallographic structures of trithiadiazepines\", Journal of the Chemical Society, Chemical Communications, pp. 398, 1985."},{"id":"https://doi.org/10.1039/c39840000055","unstructured":"S.T.A.K. Daley, C.W. Rees, and D.J. Williams, \"1,3,5,2,4-Trithiadiazepines and 1,3,5,2,4,6-trithiatriazepines, new 10? heteroaromatic systems\", Journal of the Chemical Society, Chemical Communications, pp. 55, 1984."},{"id":"https://doi.org/10.1039/c39910000942","unstructured":"P.N. Jagg, P.F. Kelly, H.S. Rzepa, D.J. Williams, J.D. Woollins, and W. Wylie, \"The preparation, X-ray crystal structure and theoretical study of [CoCp 2 ][S 3 N 3 ], (Cp = cyclopentadienyl), a novel stacking compound incorporating multiple C\u2013H \u22ef N(p \u03c0 ) interactions\", J. Chem. Soc., Chem. Commun., vol. 0, pp. 942-944, 1991."},{"id":"https://doi.org/10.1002/cber.19951280103","unstructured":"A. Haas, and M. Pryka, \"New Pathways in Tellurium\u2010Chalkogen\u2010Nitrogen Chemistry: Preparations, Structures, and Properties of Telluraheterocycles\", Chemische Berichte, vol. 128, pp. 11-22, 1995."},{"id":"https://doi.org/10.1016/0277-5387(96)00223-9","unstructured":"J. Galan-Mascaros, A.M. Slawin, J. Derek Woollins, and D.J. Williams, \"\u03c0-facial interactions between Cl\u2212 and [S4N3]+. X-ray crystal structure of [S4N3]Cl\", Polyhedron, vol. 15, pp. 4603-4605, 1996."},{"id":"https://doi.org/10.1142/12397","unstructured":"T. Chivers, and R.S. Laitinen, \"Chalcogen\u2013Nitrogen Chemistry\", 2021."},{"id":"https://doi.org/10.1021/om00138a016","unstructured":"C.G. Marcellus, R.T. Oakley, W.T. Pennington, and A.W. Cordes, \"Titanium sulfur nitrogen heterocycles: preparation and molecular structures of titanocene trisulfur tetranitride (.eta.5-C5H5)2TiS3N4 and titanocene trisulfur dinitride (.eta.5-C5H5)2TiS3N2\", Organometallics, vol. 5, pp. 1395-1400, 1986."},{"id":"https://doi.org/10.5281/zenodo.22195764","unstructured":"H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP G = -2649.576493\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22199646","unstructured":"H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22193016","unstructured":"H. Rzepa, \"Cp2TiS3N2, MN15L/Def2-TZVPP G = -2540.173075\", 2026."},{"id":"https://doi.org/10.1002/jcc.25873","unstructured":"E.D. Glendening, C.R. Landis, and F. Weinhold, \"NBO 7.0 : New vistas in localized and delocalized chemical bonding theory\", Journal of Computational Chemistry, vol. 40, pp. 2234-2241, 2019."},{"id":"https://doi.org/10.5281/zenodo.22874369","unstructured":"H. Rzepa, \"Reees 8 (MOs) NBO\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22876817","unstructured":"H. Rzepa, \"Reees 8 (MOs) NMR Bq\", 2026."},{"id":"https://doi.org/10.1021/cr030092l","unstructured":"H.S. Rzepa, \"M\u00f6bius Aromaticity and Delocalization\", Chemical Reviews, vol. 105, pp. 3697-3715, 2005."},{"id":"https://doi.org/10.1016/j.comptc.2014.09.028","unstructured":"P.L. Ayers, R.J. Boyd, P. Bultinck, M. Caffarel, R. Carb\u00f3-Dorca, M. Caus\u00e1, J. Cioslowski, J. Contreras-Garcia, D.L. Cooper, P. Coppens, C. Gatti, S. Grabowsky, P. Lazzeretti, P. Macchi, ?. Mart\u00edn Pend\u00e1s, P.L. Popelier, K. Ruedenberg, H. Rzepa, A. Savin, A. Sax, W.E. Schwarz, S. Shahbazian, B. Silvi, M. Sol\u00e0, and V. Tsirelson, \"Six questions on topology in theoretical chemistry\", Computational and Theoretical Chemistry, vol. 1053, pp. 2-16, 2015."},{"id":"https://doi.org/10.59350/6hj5w-5w040","unstructured":"H. Rzepa, \"Exploring the effect that causes ring-size specificity of transition metals for polysulfide dianions: Cyclopentadienyl-2,6-di-isopropylphenoxy Titanium pentasulfide.\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22869370","unstructured":"H. Rzepa, \"CpCOTiS3N3 (from Rees system)\", 2026."},{"id":"https://doi.org/10.5281/zenodo.23061061","unstructured":"H. Rzepa, \"CpCOTiS3N3 (from Rees system) Compound 7c NBO7\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22869771","unstructured":"H. Rzepa, \"CpCOTiS3N3 (from Rees system) NMR Bq Isotropic = -9.8464\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22934627","unstructured":"H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP Compound 1b, G = -2649.576493 NBO7\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22232235","unstructured":"H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-TZVPP G = -2649.576493 NMR Bq Isotropic = 6.6460\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22225961","unstructured":"H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67 NMR Bq Isotropic = 6.0085\", 2026."},{"id":"https://doi.org/10.5281/zenodo.23018389","unstructured":"H. Rzepa, \"Cp2TiSSNSN, MN15L/Def2-TZVPP G = -2540.194865, DG = -13.67 Compound 2 NBO7\", 2026."},{"id":"https://doi.org/10.1021/ol0518333","unstructured":"H.S. Rzepa, \"A Double-Twist M\u00f6bius-Aromatic Conformation of [14]Annulene\", Organic Letters, vol. 7, pp. 4637-4639, 2005."},{"id":"https://doi.org/10.1021/ol703129z","unstructured":"H.S. Rzepa, \"Lemniscular Hexaphyrins as Examples of Aromatic and Antiaromatic Double-Twist M\u00f6bius Molecules\", Organic Letters, vol. 10, pp. 949-952, 2008."},{"id":"https://doi.org/10.1021/ja710438j","unstructured":"S.M. Rappaport, and H.S. Rzepa, \"Intrinsically Chiral Aromaticity. Rules Incorporating Linking Number, Twist, and Writhe for Higher-Twist M\u00f6bius Annulenes\", Journal of the American Chemical Society, vol. 130, pp. 7613-7619, 2008."},{"id":"https://doi.org/10.5281/zenodo.22830870","unstructured":"H. Rzepa, \"Cp2TiSNNSS MN15L/Def2-TZVPP, G = -2540.188689 NMR Bq Isotropic = 8.3780\", 2026."},{"id":"https://doi.org/10.5281/zenodo.22933586","unstructured":"H. Rzepa, \"Cp2TiS3N4, MN15L/Def2-QZVPP Compound 1b, G = -2649.576493 NBO (not 7)\", 2026."},{"id":"https://doi.org/10.5281/zenodo.23034010","unstructured":"H. Rzepa, \"Cp2TiS3N4, wB97XD/Def2-TZVPP Compound 1b, G = -2649.576493 NBO (not 7)\", 2026."},{"id":"https://doi.org/10.5281/zenodo.23039008","unstructured":"H. Rzepa, \"Cp2TiS3N4, wB97XD/Def2-TZVPP Compound 1b, G = -2649.576493 NBO7\", 2026."}],"rid":"63h5p-zx280","summary":"Metalla-aromatics have been defined as metallacycles that are derived from the formal replacement of a carbon atom in the framework of an organic aromatic ring with a metal fragment.. Here I explore whether this simple definition can be broadened to sulfur-nitrogen rings which contain few, if indeed any,,, carbon atoms and which also happen to [\u2026]","tags":["Interesting Chemistry"],"title":"Unrecognised inorganic metalla-aromatic rings? The mystery of (cyclo-N,S)-titanocenes.","updated_at":1791013684,"url":"https://www.ch.ic.ac.uk/rzepa/blog/?p=32123","version":"v1"},{"authors":[{"affiliation":[{"name":"Imperial College London, Chemistry"}],"contributor_roles":[],"family":"Rzepa","given":"Henry","url":"https://orcid.org/0000-0002-8635-8390"}],"blog":{"authors":[{"name":"Henry Rzepa","url":"https://orcid.org/0000-0002-8635-8390"}],"community_id":"8fb94c86-e95f-41cf-aac2-a2877ffc1b5f","created":1693094400,"current_feed_url":null,"description":"Chemistry with a twist","doi":"https://doi.org/10.59350/rzepa","favicon":"https://rogue-scholar.org/api/communities/8fb94c86-e95f-41cf-aac2-a2877ffc1b5f/logo","feed_format":"application/atom+xml","feed_url":"https://www.ch.ic.ac.uk/rzepa/blog/?feed=atom","filter":null,"generator":"WordPress","home_page_url":"https://www.ch.ic.ac.uk/rzepa/blog","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"rzepa","status":"active","subfield":"1606","title":"Henry Rzepa's Blog","updated":1791013525,"use_api":true},"blog_name":"Henry Rzepa's Blog","blog_slug":"rzepa","content_html":"
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The molecule below was characterised in 1996[1] and given the name tris(dithiolene)vanadium (IV). No attempt was made in the original article to give this molecule a [2] Lewis structure using Lewis electron pair bonds. This blog will explore some of the issues that arise when this is attempted.1

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NAMPOG.

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The name given to the molecule by the chemists who made it reflects the ligand used, which we can represent as cis-HS-CH=CH-SH (via its di-sodium salt and reaction with VCl3). Its entry in the Cambridge crystal database is NAMPOG (which carries only the slightest of semantic or structural information). The chemical name however does carry some further information, namely the designation tris implies three fold symmetry (D3h in this case), and hence that all three ligands are in fact identical (structurally).

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A nominal first stab at a Lewis electron pair representation reflecting this symmetry might be as shown above.\u00a0At this point we hit a logical problem with the final component of the assigned name; the formal oxidation state of the metal is designated IV. However, three moles of (-)S-CH=CH-S(-) imply the ligands carry a formal charge of 6-, and that therefore the metal must be 6+, or VI. Six however is not an oxidation state normally exhibited by vanadium. Why did the original discoverers designate it IV? Well, because careful electron counting reveals the system as a whole has 161 electrons, of which 71 are designated as valence electrons, and hence it must have one unpaired valence electron. In the representation above, that electron is shown resident on the V atom with a dot, and the ESR spectrum measured for the molecule turns out to be apparently characteristic of V(IV) systems (they do not mention whether they also compared the spectra with those derived from genuine examples of \u00a0V(II), see below). This implies (as the authors note) that a total of only 4- must be delocalized over the three dithiolene ligands.

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Returning to our electron counting, of the remaining 70 valence electrons, 24 electrons are implicit above as twelve sulfur lone pairs (which are sometimes shown as double dots, but their explicit inclusion here would cause clutter) and so we presume the remaining 46 electrons must be in Lewis-like electron pair bonds. Well, the structure above implies 24 such bonds (the six C-H lines, as well as the \u00a0Hs are also omitted by convention, again to avoid clutter!). We can begin to see why the original article lacks a Lewis structure, since the one above contains too many electrons (48 rather than 46).

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How might one proceed to rescue the situation? Because a great many possible Lewis structures could be drawn, we have to learn a little more about the molecule and seek recourse in the bond lengths measured for the system. The most obvious is the C-C length, which turns out to be 1.36\u00c5, a value significantly longer than expected for a C=C double (i.e. a four electron) bond, but a little shorter than the 3-electron bond found in e.g. benzene.

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A second attempt at a Lewis structure

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The Lewis structure (one of three equivalent ones) now has 5 lines in the C-C region, or ~3.3 electrons per C-C bond averaged over three ligands, which seems to match the length a little better. It also has 25 lines representing nominal electron pairs and ten sulfur lone pairs, a total of 70 electrons. The net effect of this representation is to transfer two electrons from the sulfur lone pairs to the vanadium, and hence to reduce the formal charge at the metal from 6+ to 4+, or to V(IV). This sort of behaviour, where electrons can be borrowed from a ligand and used to reduce (or oxidise) the metal they are coordinated to is called non-innocent behaviour. The dithiolene ligand is notoriously non-innocent. It results in this case in our innocent assumptions that bonds are defined by an integer number of electrons [2,(3),4,(5) or 6 as in Lewis’ original classifications] are no longer adequate, and that non-integer descriptors must also be used.

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There is still one counting rule we have not inspected. To complete its valence shell to reach Kr, V needs 18 valence electrons. The representation above gives it 13. So how about the following, which ends up with a valence shell of 17 electrons for vanadium (and an oxidation state of V(II))?

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Third time lucky?

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This implies that the V-S bonds might be a little shorter than normal. Well in NAMPOG its 2.35\u00c5, perhaps slightly shorter than a typical V-S single bond of ~2.4\u00c5, but in fact we are now down at the noise level, and its clear that we have probably reached (if not exceeded) the limit of semantic interpretation of the Lewis model. In this case, only three (of 100s of possible) Lewis structures have been discussed, and of course they were selected only because we had some experimental information to discriminate between them. And we must be aware that whilst Lewis structures are the simplest way of analysing the electron distribution in a molecule, far more sophisticated analyses are nowadays possible. The real question is which analysis can actually result in a greater insight into the molecule? But the least that can be said about molecule NAMPOG is that it causes one to think about the problems of representing bonding (I will draw the line however at using this example in my university admissions interviews!).

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1 I thank J. P. P. (Jimmy) Stewart for drawing this molecule on my blackboard \u00a0and hence provoking this blog post.

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References

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  1. M. Kondo, S. Minakoshi, K. Iwata, T. Shimizu, H. Matsuzaka, N. Kamigata, and S. Kitagawa, \"Crystal Structure of a Tris(dithiolene) Vanadium(IV) Complex Having Unprecedented <i>D</i>3<i>h</i> Symmetry\", Chemistry Letters, vol. 25, pp. 489-490, 1996. https://doi.org/10.1246/cl.1996.489\n\n
    2. \n
  2. G.N. Lewis, \"THE ATOM AND THE MOLECULE.\", Journal of the American Chemical Society, vol. 38, pp. 762-785, 1916. https://doi.org/10.1021/ja02261a002\n\n
    3. \n
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","doi":"https://doi.org/10.59350/rncje-xe063","guid":"http://www.ch.ic.ac.uk/rzepa/blog/?p=2559","image":"https://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2010/09/V1.jpg","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1285545600,"reference":[{"id":"https://doi.org/10.1246/cl.1996.489","unstructured":"M. Kondo, S. Minakoshi, K. Iwata, T. Shimizu, H. Matsuzaka, N. Kamigata, and S. Kitagawa, \"Crystal Structure of a Tris(dithiolene) Vanadium(IV) Complex Having Unprecedented D3h Symmetry\", Chemistry Letters, vol. 25, pp. 489-490, 1996."},{"id":"https://doi.org/10.1021/ja02261a002","unstructured":"G.N. Lewis, \"THE ATOM AND THE MOLECULE.\", Journal of the American Chemical Society, vol. 38, pp. 762-785, 1916."}],"rid":"knbnq-h9b96","summary":"The molecule below was characterised in 1996 and given the name tris(dithiolene)vanadium (IV). No attempt was made in the original article to give this molecule a Lewis structure using Lewis electron pair bonds.","tags":["Interesting Chemistry","Cambridge","Chemical Name","Historical","Metal"],"title":"(Almost) 100 years of Lewis structures: are they still fit for purpose?","updated_at":1791013424,"url":"https://www.ch.ic.ac.uk/rzepa/blog/?p=2559","version":"v1"},{"authors":[{"affiliation":[{"id":"https://ror.org/04aj4c181","name":"Technische Informationsbibliothek (TIB)"}],"contributor_roles":[],"family":"R\u00fccknagel","given":"Jesko","url":"https://orcid.org/0000-0001-8824-8390"}],"blog":{"authors":null,"community_id":"db0d8909-9e37-46d0-b16c-0551f575e86b","created":1749772800,"current_feed_url":null,"description":"Das Blog der TIB \u2013 Leibniz-Informationszentrum Technik und Naturwissenschaften und Universit\u00e4tsbibliothek","doi":"https://doi.org/10.65527/tib","favicon":"https://rogue-scholar.org/api/communities/db0d8909-9e37-46d0-b16c-0551f575e86b/logo","feed_format":"application/atom+xml","feed_url":"https://blog.tib.eu/feed/atom/","filter":null,"generator":"WordPress","home_page_url":"https://blog.tib.eu/","issn":null,"language":"deu","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.65527","relative_url":null,"secure":true,"slug":"tib","status":"active","subfield":"1802","title":"TIB-Blog","updated":1790929692,"use_api":true},"blog_name":"TIB-Blog","blog_slug":"tib","content_html":"

Mit SavE Niedersachsen \u2013 Sicherheit f\u00fcr das audiovisuelle Erbe Niedersachsens ist seit Juli 2026 ein weiteres Projekt an die Landesinitiative Langzeitarchivierung Niedersachsen (LiLA.NDS) angebunden. Das Andockprojekt wird vom Filminstitut Hannover und der Bibliothek der Hochschule Hannover in Zusammenarbeit mit der TIB durchgef\u00fchrt. F\u00fcr die Umsetzung des Projekts ist Johanna Kolmer als wissenschaftliche Projektmitarbeiterin neu zum Team des Filminstituts hinzugekommen. Begleitet wird das Projekt von Prof. Dr. Klaus Gantert, Direktor des Filminstituts, und Thorsten Hoppe M.A., Gesch\u00e4ftsf\u00fchrer des Filminstituts.

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Im Mittelpunkt stehen die digitalen und digitalisierten audiovisuellen Best\u00e4nde des Filminstituts. Anhand dieser Best\u00e4nde werden Strategien und Arbeitsabl\u00e4ufe f\u00fcr ihre digitale Langzeitarchivierung sowie f\u00fcr die nachhaltige Sicherung der zugeh\u00f6rigen Meta- und Forschungsdaten entwickelt und erprobt. Die dabei gewonnenen Erfahrungen sollen zugleich dazu beitragen, \u00fcbertragbare L\u00f6sungsans\u00e4tze f\u00fcr kleinere Kulturerbe-Einrichtungen in Niedersachsen zu entwickeln.

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K\u00f6nnen Sie Ihre Einrichtung und deren Sammlungsschwerpunkte kurz vorstellen?

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Das Filminstitut Hannover ist eine wissenschaftliche Einrichtung der Hochschule Hannover, die sich der Sammlung, Dokumentation, Erschlie\u00dfung und Erforschung von Filmen und filmhistorischen Materialien mit besonderem Bezug zu Hannover und Niedersachsen widmet. Die Best\u00e4nde des Filminstituts Hannover umfassen unter anderem Amateur- und Dokumentarfilme, Produktionsarchive sowie umfangreiche regionalgeschichtliche Film- und Videosammlungen.

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Blick in den Archivbestand des Filminstituts Hannover. Foto: Filminstitut Hannover/Hochschule Hannover
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Viele dieser Aufnahmen stellen einzigartige audiovisuelle Quellen dar. Sie dokumentieren gesellschaftliche Entwicklungen, stadt- und regionalgeschichtliche Prozesse sowie Aspekte des Alltags in Niedersachsen \u00fcber mehrere Jahrzehnte hinweg.

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Gibt es ein digitales Objekt oder eine Sammlung, die Ihnen besonders am Herzen liegt?

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Besonders interessant ist f\u00fcr mich aktuell der Bestand zur EXPO 2000, den das Filminstitut 2025 vom EXPOSEEUM Hannover \u00fcbernommen hat.

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Filmbild, EXPO 2000 Hannover, Bau007. Foto: Filminstitut Hannover/Hochschule Hannover
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Er umfasst mehr als 2.000 Filme und dokumentiert die Weltausstellung aus unterschiedlichen Perspektiven \u2013 von den Vorbereitungen und dem Bau des Ausstellungsgel\u00e4ndes bis hin zu Veranstaltungen und den eigentlichen Ausstellungstagen.

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Der Bestand ist insbesondere deshalb von Interesse, weil die EXPO 2000 ein pr\u00e4gendes Ereignis f\u00fcr Hannover war und das Filmmaterial zugleich zentrale Themen und Diskurse der damaligen Zeit dokumentiert, etwa Zukunftsvorstellungen, Globalisierung, Nachhaltigkeit und technologischen Wandel.

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Die gro\u00dfe Menge und Heterogenit\u00e4t des Materials macht den Bestand zudem f\u00fcr Fragestellungen der digitalen Langzeitarchivierung besonders relevant.

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Was motiviert Sie, Ihre digitalen Best\u00e4nde zu archivieren? Gab es einen Ausl\u00f6ser, der den Ansto\u00df gegeben hat, sich mit der digitalen Langzeitarchivierung auseinanderzusetzen?

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Das Filminstitut digitalisiert seine historischen Filmbest\u00e4nde bereits seit vielen Jahren. Im Zuge dieser kontinuierlichen Digitalisierung ist ein umfangreicher digitaler Bestand entstanden. Gleichzeitig zeigt sich, dass die Digitalisierung allein noch keine dauerhafte Sicherung und langfristige Nutzbarkeit der Materialien gew\u00e4hrleistet.

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Digitale Dateien unterliegen eigenen Risiken: Speichermedien k\u00f6nnen ausfallen, Dateien k\u00f6nnen besch\u00e4digt werden, Dateiformate langfristig obsolet werden und relevante Kontextinformationen verloren gehen. Gerade bei umfangreichen audiovisuellen Best\u00e4nden sind daher verl\u00e4ssliche und nachvollziehbar dokumentierte Strukturen erforderlich, um die Integrit\u00e4t, Interpretierbarkeit und Nutzbarkeit der Daten langfristig sicherzustellen. Diese Herausforderung bildet einen wesentlichen Ausgangspunkt f\u00fcr SavE Niedersachsen.

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Welche Unterst\u00fctzung ist f\u00fcr Sie im Projekt besonders wertvoll?

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Besonders wertvoll ist f\u00fcr uns der fachliche Austausch mit der TIB und den weiteren Einrichtungen innerhalb von LiLA.NDS. Die digitale Langzeitarchivierung umfasst zahlreiche technische, organisatorische und konzeptionelle Fragestellungen, bei deren Bearbeitung wir von bereits vorhandenen Erfahrungen und entsprechender Expertise profitieren k\u00f6nnen.

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Gleichzeitig bietet die Zusammenarbeit die M\u00f6glichkeit, die spezifischen Anforderungen audiovisueller Best\u00e4nde in den gemeinsamen Austausch einzubringen. Besonders wichtig ist dabei die gemeinsame Entwicklung und Erprobung praktikabler und m\u00f6glichst \u00fcbertragbarer L\u00f6sungsans\u00e4tze. Der Wissenstransfer innerhalb des Netzwerks erm\u00f6glicht es, unterschiedliche Perspektiven zusammenzuf\u00fchren und Herausforderungen der digitalen Langzeitarchivierung gemeinschaftlich zu bearbeiten.

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Blogreihe \"LiLA.NDS\"

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Im Rahmen einer begleitenden Blogreihe werden wir regelm\u00e4\u00dfig \u00fcber den Projektfortschritt Landesinitiative Langzeitarchivierung Niedersachsen (kurz LiLA) berichten. So erhalten Interessierte au\u00dferhalb des Projektkonsortiums Einblicke in die Arbeit von LiLA. In den kommenden Beitr\u00e4gen stellen sich die beteiligten Einrichtungen vor, berichten \u00fcber ihre zu archivierenden Best\u00e4nde und erl\u00e4utern, warum die digitale Langzeitarchivierung f\u00fcr sie von besonderer Bedeutung ist. Damit ist die Blogreihe eine wichtige S\u00e4ule in der geplanten Wissensbasis, die es dem Projekt erm\u00f6glicht, Best Practices vorzustellen und Einblicke in die Umsetzungsphase zu geben.
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","doi":"https://doi.org/10.65527/qt0rp-2fr16","guid":"https://blog.tib.eu/?p=33814","image":"https://blog.tib.eu/wp-content/uploads/2026/09/Filmbild-EXPO-2000-Hannover-Bau007.-\u00a9-Filminstitut-Hannover-Hochschule-Hannover.jpg","language":"de","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790899200,"rid":"dhf3n-2w009","summary":"Mit SavE Niedersachsen \u2013 Sicherheit f\u00fcr das audiovisuelle Erbe Niedersachsens ist seit Juli 2026 ein weiteres Projekt an die Landesinitiative Langzeitarchivierung Niedersachsen (LiLA.NDS) angebunden. Das Andockprojekt wird vom Filminstitut Hannover und der Bibliothek der Hochschule Hannover in Zusammenarbeit mit der TIB durchgef\u00fchrt.","tags":["FORSCHUNG & PROJEKTE","LiLA.NDS","Lizenz:CC-BY-4.0-INT","Digitale Langzeitarchivierung","Landesinitiative Langzeitarchivierung Niedersachsen"],"title":"Digitales Kulturerbe bewahren \u2013 SavE Niedersachsen sichert audiovisuelle Best\u00e4nde des Filminstituts Hannover","updated_at":1791012614,"url":"https://blog.tib.eu/2026/10/02/digitales-kulturerbe-bewahren-save-niedersachsen-sichert-audiovisuelle-bestaende-des-filminstituts-hannover/","version":"v1"},{"authors":[{"affiliation":[{"name":"Sky Publishing Corp, Sky & Telescope"}],"contributor_roles":[],"family":"Wedel","given":"Mathew","url":"https://orcid.org/0000-0001-6082-3103"}],"blog":{"authors":[{"name":"Mike Taylor"}],"community_id":"0e13541f-417e-46c0-a859-65927249df72","created":1675209600,"current_feed_url":null,"description":"SV-POW! ... All sauropod vertebrae, except when we're talking about Open Access. ISSN 3033-3695","doi":"https://doi.org/10.59350/svpow","favicon":"https://rogue-scholar.org/api/communities/0e13541f-417e-46c0-a859-65927249df72/logo","feed_format":"application/atom+xml","feed_url":"https://svpow.com/feed/atom/","filter":null,"generator":"WordPress.com","home_page_url":"https://svpow.com","issn":"3033-3695","language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"svpow","status":"active","subfield":"1911","title":"Sauropod Vertebra Picture of the Week","updated":1790926474,"use_api":true},"blog_name":"Sauropod Vertebra Picture of the Week","blog_slug":"svpow","content_html":"

If you travel in the same circles I do, you probably know that my friend and colleague Mark Witton is working on a speculative biology book, Dinosaurs Evolved, that takes a fresh look at what life on Earth might be like now had the asteroid missed and the K-Pg extinction never happened. As a lifelong spec-bio fan, I’m stoked for that project. Speculative sauropods have given me a lot to think about, especially in the past few years, so I thought it would be fun to revisit some in this post. Maybe all? There aren’t a ton of examples. If you know of any I missed here, sing out in the comments. (I’m not including any from the Speculative Dinosaur Project out of lack of familiarity — the project was basically dead by the time I would have started following it — and I’m not sure any are currently accessible anyway.)

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Rather than proceeding chronologically, I’m going to start with my favorites and proceed in the direction of the most-loathed, for reasons that will become apparent later on. Back in 2010, Memo K\u00f6semen kindly let us — Mike, Darren, and me — debut his Brontosapiens here on SV-POW!, and give our thoughts on it. I’m not going to say much about this critter in this post, mostly because I think our ideas from 16 years ago hold up pretty well, and you can just go read the original post if you’re curious.

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Pp. 42-43 in The New Dinosaurs. (c) Dougal Dixon and Breakdown Press 2025.

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Of course the OG speculative sauropods are the ones dreamt up by Dougal Dixon for The New Dinosaurs (1988), the recent reprint of which I reviewed here. In addition to the ones shown above, there are a couple more in the book: a dwarf island sauropod, which we now know actually happened more than once, and the Rajaphant, which is basically an unremarkable large titanosaur. Of the ones in the above spread, the Lumber has a trunk and is actually built for it, unlike any real-world sauropods discovered so far, and the Turtosaur takes titanosaur osteoderms to their logical conclusion. I like ’em both. The box on the far left shows the skeleton of a group of slender-bodied running sauropods that flourished only briefly during Dixon’s alternate Cenozoic.

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I’m not going to say much about the brontosaurs in Peter Jackson’s King Kong (2005), because they’re not really attempts at spec bio, but rather deliberately old-fashioned Charles R. Knight/Rudolph Zallinger-esque productions realized in CG. I’ll say of the movie that it has a lot of dinosaurs but not particularly interesting ones; if you thought that the Jurassic Park/World movies were too realistic and you’d prefer your dinosaurs to look like cliches from decades past and act like voracious monsters, King Kong has you covered. That said, as monster fights go, King Kong vs. three V. rexes is a banger.

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Much more interesting from a spec bio perspective is a book that accompanied the movie, The World of Kong: A Natural History of Skull Island. It explains the fictional evolutionary backstory of the Skull Island critters from the movie, both the ones that made it to the screen, and many others that did not. Among those never realized on screen are two sauropods. The first, shown above, is Asperdorsus (“rough back”), which has spines on its back and hanging from its neck. This is pretty much just a spiny Diplodocus and it wouldn’t surprise me if someone dug one of these up in Montana while I was writing this post.

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Then there’s this thing, Diablosaurus, which I have an almost visceral dislike of, for many reasons. First off, it’s boring. It’s just a dinosaur squeezed into the shape of a rhinoceros. In a world with the full-tilt wackiness of actual ceratopsians (f’rinstance) — of which there were also fictional examples on Skull Island! — a rhino-alike with horns but no frill is both uninspired and unexciting. Also, hello, Iguanodon from the 1830s is calling.

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But it gets worse. Although the skeletal diagram shows that this dumb thing was clearly an ornithischian, or at least had an ornithischian pelvis, the text says that it’s an aberrant sauropod. Er, wut? I guess some Camarasaurus finally got drunk enough to evolve into an ornithischian and then into a mammal-shaped ornithischian. Of course it would.

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I should give some credit to Diablosaurus, though, because it forced me to think about why I hated it so much. That got me thinking about what actual sauropods did, evolutionarily (be large-bodied, long-necked and long-tailed, graviportal, non-oral-processing oviparous quadrupedal herbivores), and what they did not do (er, pretty much everything else, including being Diablosaurus-like).

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My “nontosaurs”: the gazelleopod, antlertitan, and poseidonposeidon.

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And that led to my “Sauropod Heresies” mini-paper and talk for the Tate 2024 conference (link), which I tuned up with another year’s worth of thoughts for DinoCon 2025. The image above is a doodle I did for those talks, illustrating some of the paths not taken in sauropod evolution. If real sauropods were brontosaurs, I call the ‘forbidden’ experiments, including Diablosaurus, the nontosaurs.

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To bring this full circle, Mark Witton has been kind enough to share some behind-the-scenes thinking for Dinosaurs Evolved, and he’s thought of some ways out of what we might call “brontosaur lock-in” that hadn’t occurred to me, but which I think are eminently plausible. One of them is the subject of a recent post on his Patreon. I’ll say no more for now, but let’s circle back after the book is out, to revisit both speculative sauropods and the real and imagined limits on the sauropod body plan.

","doi":"https://doi.org/10.59350/vweh2-9sk08","guid":"https://svpow.com/?p=25978","image":"https://svpow.wordpress.com/wp-content/uploads/2010/06/nemos-brontosapiens.png?w=480","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790899200,"rid":"34kn1-jmv09","summary":"If you travel in the same circles I do, you probably know that my friend and colleague Mark Witton is working on a speculative biology book, Dinosaurs Evolved, that takes a fresh look at what life on Earth might be like now had the asteroid missed and the K-Pg extinction never happened.","tags":["Brontosapiens","Cenozoic Dinosaurs","Dougal Dixon","Speculation","Speculative Biology"],"title":"Speculative sauropods","updated_at":1791012611,"url":"https://svpow.com/2026/10/02/speculative-sauropods/","version":"v1"},{"authors":[{"affiliation":[{"name":"Freie Universit\u00e4t Berlin, Open Research Office Berlin"}],"contributor_roles":[],"family":"Duine","given":"Maaike","url":"https://orcid.org/0000-0003-3412-7192"}],"blog":{"authors":null,"community_id":"52aefd81-f405-4349-b080-754395a5d8b2","created":1694476800,"current_feed_url":null,"description":null,"doi":"https://doi.org/10.59350/oaberlin","favicon":"https://rogue-scholar.org/api/communities/52aefd81-f405-4349-b080-754395a5d8b2/logo","feed_format":"application/atom+xml","feed_url":"https://blogs.fu-berlin.de/open-research-berlin/feed/atom/","filter":null,"generator":"WordPress","home_page_url":"https://blogs.fu-berlin.de/open-research-berlin","issn":null,"language":"deu","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"oaberlin","status":"active","subfield":"1802","title":"Open Research Blog Berlin","updated":1790941290,"use_api":true},"blog_name":"Open Research Blog Berlin","blog_slug":"oaberlin","content_html":"

Orte und Tools f\u00fcr digitales, nicht-kommerzielles Publizieren

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Faires, wissenschaftsgeleitetes Open-Access-Publizieren gewinnt zunehmend an Bedeutung, nicht zuletzt durch die Priorisierungsagenda der BUA-Einrichtungen zur Umsetzung des Open-Science-Leitbilds und das Positionspapier zu Open Research der Berliner Landesinitiative. Doch welche Alternativen zu etablierten, oft kommerziellen Publikationswegen gibt es eigentlich, und wie funktionieren sie?

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In diesem einst\u00fcndigen Lunch Meeting stellen wir Ihnen ausgew\u00e4hlte Orte und Tools f\u00fcr digitales Publizieren vor, von fachspezifischen Verlagen wie SciPost oder Open Library of Humanities bis hin zu neuen Publishing-Tools wie Octopus und ResearchEquals. Ein Praxisbericht von Forschenden erg\u00e4nzt die Vorstellung der Publishing-Tools. Dar\u00fcber hinaus geben wir Einblick in die Angebote von Berlin Universities Publishing. Im Anschluss bleibt ausreichend Zeit f\u00fcr Fragen und Diskussion.

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Das Meeting findet im Rahmen der internationalen Open Access Week statt und richtet sich an alle Forschenden, die mehr \u00fcber faire und offene Publikationsm\u00f6glichkeiten erfahren m\u00f6chten. Das Thema der diesj\u00e4hrigen Open Access Week lautet \"The Cost of Knowledge\": Entsprechend nehmen wir das Motto zum Anlass, um Alternativen zu kommerziell ausgerichteten Publikationsm\u00f6glichkeiten vorzustellen.

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Offen und fair Publizieren: Orte und Tools f\u00fcr digitales, nicht-kommerzielles Publizieren\n-Wann: Montag, 19.10.2026, 13:00-14:00 Uhr\n-Wo: Online\n-Registrierung: Anmeldung per Webex
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Organisiert von:

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","doi":"https://doi.org/10.59350/xcjqw-q0t82","guid":"https://blogs.fu-berlin.de/open-research-berlin/?p=4343","language":"de","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1789603200,"rid":"99595-v5p57","summary":"Orte und Tools f\u00fcr digitales, nicht-kommerzielles Publizieren Faires, wissenschaftsgeleitetes Open-Access-Publizieren gewinnt zunehmend an Bedeutung, nicht zuletzt durch die Priorisierungsagenda der BUA-Einrichtungen zur Umsetzung des Open-Science-Leitbilds und das Positionspapier zu Open Research der Berliner Landesinitiative.","tags":["Allgemein","Aktuelles","Berlin","Bibliotheken","Open Access"],"title":"Online Lunch Meeting: Offen und fair Publizieren","updated_at":1791012607,"url":"https://blogs.fu-berlin.de/open-research-berlin/2026/09/17/online-lunch-meeting-offen-und-fair-publizieren/","version":"v1"},{"authors":[{"contributor_roles":[],"family":"Priego","given":"Ernesto"}],"blog":{"authors":[{"name":"Ernesto Priego"}],"community_id":"ae617b4e-ce60-495f-a839-e05f4c0da6b5","created":1698796800,"current_feed_url":null,"description":"Ernesto Priego's blog. A personal repository of stuff.","doi":"https://doi.org/10.59350/ernestopriego","favicon":"https://rogue-scholar.org/api/communities/ae617b4e-ce60-495f-a839-e05f4c0da6b5/logo","feed_format":"application/atom+xml","feed_url":"https://ernestopriego.com/feed/atom/","filter":null,"generator":"WordPress.com","home_page_url":"https://ernestopriego.com","issn":null,"language":"eng","license":"https://creativecommons.org/licenses/by/4.0/legalcode","prefix":"10.59350","relative_url":null,"secure":true,"slug":"ernestopriego","status":"active","subfield":"1213","title":"Everything is Connected","updated":1790950930,"use_api":true},"blog_name":"Everything is Connected","blog_slug":"ernestopriego","content_html":"
\"Ernesto
Yours Truly (left) with graphic novelists Francisco de la Mora, Gemma Plum and Zara Slattery
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Panels & Perspectives: Panel on Disability and Neurodiversity in Comics took place at AG01, Thursday, October 1st 2026 in the College Building, City St George’s, University of London. The panel successfully explored how graphic novels can challenge stereotypes, create connections and invite readers to the world from different perspectives. The session was well attended with the room at full capacity.

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Calling upon the powerful true stories behind their work, graphic novelists Francisco de la Mora, Gemma Plum and Zara Slattery examined how comics can make visible experiences that are often overlooked, opening up conversations about disability, neurodiversity, care and belonging.

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The event coincided with the official UK release of Gemma Plum's The Great Marc Evers. The True Story of a Champion Against All Odds (Selfmadehero 2026), which tells in comics form 'the inspiring life story of one of the greatest Paralympic swimming champions, and his family that stopped focusing on a \"no\" to find a \"yes\".'

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Each member of the panel spoke of what had first drawn them to graphic storytelling, and made a short presentation about each of the books featured in the event, with themes related to disability and neurodiversity:

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The Most Amazing Saturday Morning Rubbish Club, by Francisco de la Mora and Bill Tuckey (Selfmadehero, 2025).

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The Great Marc Evers: The True Story of a Champion Against All Odds, by Gemma Plum, Ivo van Woerden and Marloes Dekkers (Selfmadehero 2026), and

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Coma, by Zara Slattery (Myriad Editions, 2021).

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Internal and external participants, including Human Computer Interaction Design MSc students from the 2025-26 and 2026-27 cohort, who engaged in the Q&A and chatted with the authors, bought their books and got them signed after the panel over refreshments.

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\"Gemma
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This event also provided an opportunity to talk about Ernesto's Parables of Care project creating comics about dementia care, and copies were distributed freely with participants who had not heard of the project before.

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\"Copies
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\"An
One member of the audience even did some sketch-noting during the panel in comics form!
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This activity also informally launched my Sabbatical research leave!

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This event was organised in collaboration with comics publisher Selfmadehero.

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Participants consented to being photographed for documentation purposes. Thank you to everyone who attended and participated; it was a joyous occasion.

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","doi":"https://doi.org/10.59350/ymbc3-w2j61","guid":"https://ernestopriego.com/?p=11990","image":"https://i0.wp.com/ernestopriego.com/wp-content/uploads/2026/10/image-1.jpeg?fit=2048%2C1536&ssl=1","language":"en","license":"https://creativecommons.org/licenses/by/4.0/legalcode","published_at":1790899200,"rid":"pw0n8-ynh06","summary":" Panels & Perspectives: Panel on Disability and Neurodiversity in Comics took place at AG01, Thursday, October 1 st 2026 in the College Building, City St George's, University of London. The panel successfully explored how graphic novels can challenge stereotypes, create connections and invite readers to the world from different perspectives. The session was well attended with the room at full capacity.","tags":["Comics","Events"],"title":"Panels and Perspectives: Exploring Disability and Neurodiversity Through Comics","updated_at":1791012607,"url":"https://ernestopriego.com/2026/10/02/panels-and-perspectives-exploring-disability-and-neurodiversity-through-comics/","version":"v1"}],"out_of":57709,"page":1,"per_page":10,"total-results":57709}