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Université de Fribourg

pH-dependent coordination of AgI ions by histidine: experiment, theory, and a model for SilE

Mirolo, Laurent ; Schmidt, Tobias ; Eckhardt, Sonja ; Meuwly, Markus ; Fromm, Katharina M.

In: Chemistry - A European Journal, 2013, vol. 19, no. 5, p. 1754–1761

Artificial implants and biomaterials lack the natural defense system of our body and, thus, have to be protected from bacterial adhesion and biofilm formation. In addition to the increasing number of implanted objects, the resistance of bacteria is also an important problem. Silver ions are well-known for their antimicrobial properties, yet not a lot is known about their mode of action. Silver is...

Université de Fribourg

Tautomerism in 1-phenylazo-4-naphthols: experimental results vs quantum-chemical predictions

Antonov, Liudmil ; Kurteva, Vanya ; Crochet, Aurelien ; Mirolo, Laurent ; Fromm, Katharina M. ; Angelova, Silvia

In: Dyes and Pigments, 2012, vol. 92, no. 1, p. 714–723

The reliability in the description of the tautomerism of 1-phenylazo-4-naphthol by using of HF and MP2 ab initio levels of theory and DFT methods with variety of pure GGA (OLYP), hybrid (B3LYP and B3PW91), long range corrected (LC-BLYP) and double-hybrid (B2PLYP and mPW2PLYP) functionals with large number of basis sets was estimated. In this evaluation three criteria were used: reproduction of...

Université de Fribourg

Of chains and rings: synthetic strategies and theoretical investigations for tuning the structure of silver coordination compounds and their applications

Slenters, Tünde Vig ; Sagué, Jorge L. ; Brunetto, Priscilla S. ; Zuber, Stefanie ; Fleury, Antoine ; Mirolo, Laurent ; Robin, Adeline Y. ; Meuwly, Markus ; Gordon, Oliver ; Landmann, Regine ; Daniels, Alma U. ; Fromm, Katharina M.

In: Materials, 2010, vol. 3, no. 5, p. 3407-3429

Varying the polyethyleneglycol spacer between two (iso)-nicotinic groups of the ligand systems, a large structural variety of silver coordination compounds was obtained, starting with zero-dimensional ring systems, via one-dimensional chains, helices and double-helices to two-dimensional polycatenanes. Theoretical calculations help to understand their formation and allow predictions in some...

Université de Fribourg

Coordination polymer networks: an alternative to classical polymers ?

Fromm, Katharina M. ; Sagué, Jorge L. ; Mirolo, Laurent

In: Macromolecular Symposia, 2010, vol. 291-292, no. 1, p. 75-83

This chapter of "Polymer Networks: Synthesis, Properties, Theory and Applications" provides a brief overview on metal ion containing coordination polymer networks, how and why they are made, as an alternative to classical polymers. Our focus will be polymorphism, supramolecular isomerism and pseudo-polymorphism. Examples from our group of metal ion containing coordination polymer networks with...

Université de Fribourg

Solid state tautomerism in 2-((phenylimino)methyl)naphthalene-1-ol

Nedeltcheva, Daniela ; Kamounah, Fadhil S. ; Mirolo, Laurent ; Fromm, Katharina M. ; Antonov, Liudmil

In: Dyes and Pigments, 2009, vol. 83, no. 1, p. 121-126

The solid state tautomerism of 2-((phenylimino)methyl)naphthalene-1-ol was studied using X-ray measurements and absorption spectroscopy. In the solid state, the keto tautomer predominates. The observed shift in the equilibrium from the enol (dilute solution) to the keto (solid state) forms is explained by the formation of dye aggregates using ab initio quantum chemical calculations.

Université de Fribourg

Silver nanoparticle formation in different sizes induced by peptides identified within split-and-mix libraries

Belser, Kirsten ; Slenters, Tünde Vig ; Pfumbidzai, Conelious ; Upert, Grégory ; Mirolo, Laurent ; Fromm, Katharina M. ; Wennemers, Helma

In: Angewandte Chemie International Edition, 2009, vol. 48, no. 20, p. 3661-3664

Split-and-mix libraries are an excellent tool for the identification of peptides that induce the formation of Ag nanoparticles in the presence of either light or sodium ascorbate to reduce Ag+ ions. Structurally diverse peptides were detected in colorimetric on-bead screenings that generate Ag nanoparticles of different sizes, as confirmed by SEM and X-ray powder diffraction studies

Université de Fribourg

Silver nanoparticle engineering via oligovaline organogels

Mantion, Alexandre ; Guex, A. Geraldine ; Foelske, Annette ; Mirolo, Laurent ; Fromm, Katharina M. ; Painsi, Monika ; Taubert, Andreas

In: Soft Matter, 2008, vol. 4, no. 3, p. 606-617

L-Valine-based oligopeptides with the chemical structure Z–(L-Val)₃–OMe and Z–(L-Val)₂–L-Cys(S-Bzl)–OMe form stable organogels in butanol. Both peptides are efficient gelators, but Z–(L-Val)₂–L-Cys(S-Bzl)–OMe crystallizes more readily than Z–(L-Val)₃–OMe. The two peptides can form mixed fibers, which also gel butanol. The resulting organogels are very similar to...