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Université de Fribourg

Triggered metal ion release and oxidation: ferrocene as a mechanophore in polymers

Giannantonio, Michela Di ; Ayer, Mathieu A. ; Verde-Sesto, Ester ; Lattuada, Marco ; Weder, Christoph ; Fromm, Katharina M.

In: Angewandte Chemie International Edition, 2018, vol. 57, no. 35, p. 11445–11450

The introduction of mechanophores into polymers makes it possible to transduce mechanical forces into chemical reactions that can be used to impart functions such as self‐healing, catalytic activity, and mechanochromic response. Here, an example of mechanically induced metal ion release from a polymer is reported. Ferrocene (Fc) was incorporated as an iron ion releasing mechanophore into...

Université de Fribourg

Mononuclear silver(I) complexes with 1,7-phenanthroline as potent inhibitors of Candida growth

Savić, Nada D. ; Vojnovic, Sandra ; Glišić, Biljana Đ. ; Crochet, Aurélien ; Pavic, Aleksandar ; Janjić, Goran V. ; Pekmezović, Marina ; Opsenica, Igor M. ; Fromm, Katharina M. ; Nikodinovic-Runic, Jasmina ; Djuran, Miloš I.

In: European Journal of Medicinal Chemistry, 2018, vol. 156, p. 760–773

Mononuclear silver(I) complexes with 1,7-phenanthroline (1,7-phen), [Ag(NO3-O,O′) (1,7-phen-N7)2] (1) and [Ag(1,7-phen-N7)2]X, X = ClO4− (2), CF3SO3− (3), BF4− (4) and SbF6− (5) were synthesized and structurally characterized by NMR (1H and 13C), IR and UV–Vis spectroscopy and ESI mass spectrometry. The crystal structures of 1, 3 and 4 were determined by single-crystal X-ray...

Université de Fribourg

Alpha-helical folding of SilE models upon Ag(His)(Met) motif formation

Chabert, Valentin ; Hologne, Maggy ; Sénèque, Olivier ; Walker, Olivier ; Fromm, Katharina M.

In: Chemical Communications, 2018, vol. 54, no. 74, p. 10419–10422

The SilE protein is suspected to have a prominent role in Ag+ detoxification of silver resistant bacteria. Using model peptides, we elucidated both qualitative and quantitative aspects of the Ag+-induced α-helical structuring role of His- and Met-rich sequences of SilE, improving our understanding of its function within the Sil system.

Université de Fribourg

Trithiocarbonate-functionalized PNiPAAm-based nanocomposites for antimicrobial properties

Tan, Milène ; Horvàth, Lenke ; Brunetto, Priscilla S. ; Fromm, Katharina M.

In: Polymers, 2018, vol. 10, no. 6, p. 665

In this study, four trithiocarbonate-functionalized PNiPAAms with different molecular weights were synthesized and used as a matrix to form composites with silver nanoparticles. Nanocomposites with several polymer-to-silver ratios P:Ag+ were prepared in order to evaluate the influence of silver loading. UV studies showed a thermoresponsive behavior of the nanocomposites with a...

Université de Fribourg

Early-stage sustainability evaluation of nanoscale cathode materials for lithium ion batteries

Hischier, Roland ; Kwon, Nam Hee ; Brog, Jean?Pierre ; Fromm, Katharina M.

In: ChemSusChem, 2018, vol. 11, no. 13, p. 2068–2076

Results of an early-stage sustainability evaluation of two development strategies for new nanoscale cathode materials for Li-ion batteries are reported: (i) a new production pathway for an existing material (LiCoO2) and (ii) a new nanomaterial (LiMnPO4). Nano-LiCoO2 was synthesized by a single-source precursor route at a low temperature with a short reaction time, which results in a smaller...

Université de Fribourg

A concept for stimulated proton transfer in 1-(phenyldiazenyl)naphthalen-2-ols

Hristova, S. ; Deneva, Vera V. ; Pittelkow, M. ; Crochet, Aurélien ; Kamounah, Fadhil S. . ; Fromm, Katharina M. ; Hansen, P. E. ; Antonov, Liudmil M.

In: Dyes and Pigments, 2018, vol. 156, p. 91–99

A series of aryl azo derivatives of naphthols (1–3) were studied by means of UV–Vis and NMR spectroscopy in different solvents as well as by quantum chemical calculations and X-ray analysis. Previous studies have shown that Sudan I (1) exists as a tautomeric mixture. The effect of the solvents is minimized by the existing intramolecular hydrogen bond. Therefore, the influence on the...

Université de Fribourg

Ag Nanoencapsulation for Antimicrobial Applications

Abram, Sarah-Luise ; Gagnon, Jacinthe ; Priebe, Magdalena ; Hérault, Nelly ; Fromm, Katharina M.

In: CHIMIA International Journal for Chemistry, 2018, vol. 72, no. 4, p. 249–252

Biomaterial-related infections remain a significant challenge in medicine. Antimicrobial materials on the basis of Ag nanoparticles represent a promising solution for this issue. Therefore several Ag-containing nanocontainers and nanorattles have been synthesized and characterized that exhibit remarkable control over the release of Ag+ as antimicrobial active species. Their biological...

Université de Fribourg

Versatile synthesis of chiral 6-oxoverdazyl radical ligands – new building blocks for multifunctional molecule-based magnets

Solea, Atena B. ; Wohlhauser, Tobie ; Abbasi, Parisa ; Mongbanziama, Yvan ; Crochet, Aurelien ; Fromm, Katharina M. ; Novitchi, Ghenadie ; Train, Cyrille ; Pilkington, Melanie ; Mamula, Olimpia

In: Dalton Transactions, 2018, vol. 47, no. 14, p. 4785–4789

A versatile synthetic methodology to access the first family of chiral verdazyl N,N′- chelate ligands is described and exemplified by N,N′-dimethyl-, N,N′-di-isopropyl- and N,N′-diphenyl oxoverdazyls bearing two isomers of the pinene-pyridine functional group. Their physical properties were probed by X-band EPR spectroscopy, cyclic voltammetry and DFT calculations. Preliminary...

Université de Fribourg

Amide neighbouring-group effects in peptides: phenylalanine as relay amino acid in long-distance electron transfer

Nathanael, Joses G. ; Gamon, Luke F. ; Cordes, Meike ; Rablen, Paul R. ; Bally, Thomas ; Fromm, Katharina M. ; Giese, Bernd ; Wille, Uta

In: ChemBioChem, 2018, vol. 19, no. 9, p. 922–926

In nature, proteins serve as media for long‐distance electron transfer (ET) to carry out redox reactions in distant compartments. This ET occurs either by a single‐step superexchange or through a multi‐step charge hopping process, which uses side chains of amino acids as stepping stones. In this study we demonstrate that Phe can act as a relay amino acid for long‐distance electron...