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Université de Fribourg

Ab-initio crystal structure analysis and refinement approaches of oligo p-benzamides based on electron diffraction data

Gorelik, Tatiana E. ; Streek, Jacco van de ; Kilbinger, Andreas F. M. ; Brunklaus, Gunther ; Kolb, Ute

In: Acta Crystallographica Section B, 2012, vol. 68, no. 2, p. 171-181

Ab-initio crystal structure analysis of organic materials from electron diffraction data is presented. The data were collected using the automated electron diffraction tomography (ADT) technique. The structure solution and refinement route is first validated on the basis of the known crystal structure of tri-p-benzamide. The same procedure is then applied to solve the previously unknown crystal...

Université de Fribourg

Branched polymers via ROMP of termimers

Hanik, Nils ; Kilbinger, Andreas F. M.

In: Macromolecular Rapid Communications, 2016, vol. 37, no. 6, p. 532–538

Today's olefin metathesis catalysts show high reactivity, selectivity, and functional group tolerance and allow the design of new syntheses of precisely functionalized polymers. Here the synthesis of a new end-capping reagent is investigated allowing the introduction of a highly reactive activated ester end-group at the polymer chain end as well as its prefunctionalization to directly...

Université de Fribourg

Catalytic living ring opening metathesis polymerisation: the importance of ring strain in chain transfer agents

Liu, Peng ; Yasir, Mohammad ; Kilbinger, Andreas F. M.

In: Angewandte Chemie International Edition, 2019, vol. 58, no. 43, p. 15278–15282

A recently developed catalytic living ring opening metathesis polymerisation (ROMP) was investigated using a series of reversible chain transfer agents (CTA) carrying either cyclopentene or cyclohexene rings, differing only in ring strain. All cyclopentene derivatives examined showed significantly faster reaction rates than the corresponding cyclohexene derivatives. This resulted in lower...

Université de Fribourg

Catalytic living ring-opening metathesis polymerization

Nagarkar, Amit A. ; Kilbinger, Andreas F. M.

In: Nature Chemistry, 2015, vol. 7, no. 9, p. 718–723

In living ring-opening metathesis polymerization (ROMP), a transition-metal–carbene complex polymerizes ring-strained olefins with very good control of the molecular weight of the resulting polymers. Because one molecule of the initiator is required for each polymer chain, however, this type of polymerization is expensive for widespread use. We have now designed a chain-transfer agent (CTA)...

Université de Fribourg

Catalytic living ring-opening metathesis polymerization with Grubbs’ second- and third-generation catalysts

Yasir, Mohammad ; Liu, Peng ; Tennie, Iris K. ; Kilbinger, Andreas F. M.

In: Nature Chemistry, 2019, vol. 11, no. 5, p. 488–494

In a conventional living ring-opening metathesis polymerization (ROMP), an equal number of ruthenium complexes to the number of polymer chains synthesized are required. This can lead to high loadings of ruthenium complexes when aiming for shorter polymers. Here, a reversible chain-transfer agent was used to produce living ROMP polymers from norbornene derivatives using catalytic amounts of...

Université de Fribourg

Controlling molecular self-assembly on an insulating surface by rationally designing an efficient anchor functionality that maintains structural flexibility

Hauke, Christopher M. ; Bechstein, Ralf ; Kittelmann, Markus ; Storz, Christof ; Kilbinger, Andreas F. M. ; Rahe, Philipp ; Kühnle, Angelika

In: ACS Nano, 2013, vol. 7, no. 6, p. 5491–5498

Molecular self-assembly on surfaces is dictated by the delicate balance between intermolecular and molecule–surface interactions. For many insulating surfaces, however, the molecule–surface interactions are weak and rather unspecific. Enhancing these interactions, on the other hand, often puts a severe limit on the achievable structural variety. To grasp the full potential of molecular...

Université de Fribourg

Degradable precision polynorbornenes via ring-opening metathesis polymerization

Moatsou, Dafni ; Nagarkar, Amit ; Kilbinger, Andreas F. M. ; O'Reilly, Rachel K.

In: Journal of Polymer Science Part A: Polymer Chemistry, 2016, vol. 54, no. 9, p. 1236–1242

In an attempt to introduce monomer sequence control in a growing polynorbornene via ring-opening metathesis polymerization, we employ dioxepins to efficiently determine the location of the monomers on the macromolecule backbone. Owing to the acid-labile acetal group, dioxepins allow scission of the polymer at the point of the dioxepin insertion and thus provide an indirect way to determine...

Université de Fribourg

Efficient amine end-functionalization of living ring-Opening metathesis polymers

Nagarkar, Amit A. ; Crochet, Aurelien ; Fromm, Katharina M. ; Kilbinger, Andreas F. M.

In: Macromolecules, 2012, vol. 45, no. 11, p. 4447–4453

An efficient strategy for the synthesis of monoamine end-functionalized living polymers using ring-opening metathesis polymerization with ruthenium initiators is reported. A new end-capping agent for this purpose was synthesized, and its efficiency for end-functionalization was evaluated using two common ruthenium-based initiators. Finally, terminal cross-metathesis was also explored as another...

Université de Fribourg

Enolesters as chain end-functionalizing agents for the living ring opening metathesis polymerization

Liu, Peng ; Yasir, Mohammad ; Kurzen, Helena ; Hanik, Nils ; Schäfer, Mark ; Kilbinger, Andreas F. M.

In: Journal of Polymer Science Part A: Polymer Chemistry, 2017, vol. 55, no. 18, p. 2983–2990

Functional enolethers have previously been used to introduce functional end groups at the chain end of ruthenium carbene complex initiated living ring opening metathesis polymers. Here, we investigated whether the weaker π-donating enolesters could equally be used in regio selective reactions with ruthenium carbene complexes and thus as polymer end-functionalization reagents. Enolesters such as...

Université de Fribourg

Facile synthesis of a high molecular weight amphiphilic aramid–ROMP block copolymer

Badoux, Michael ; Drechsler, Susanne ; Pal, Subhajit ; Kilbinger, Andreas F. M.

In: Macromolecules, 2017, vol. 50, no. 23, p. 9307–9314

Herein we report the facile synthesis of an amphiphilic rod–coil block copolymer obtained by the coupling of an amine-terminated poly(dimethylpropylamine norbornene imide) (PDMAPNI) and a pentafluorophenol ester-terminated poly(dimethoxybenzyl p-aminobenzoate) (PAram). Postpolymerization amide N- deprotection of the block copolymer yielded a strongly aggregating water-soluble rod– coil...