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Université de Fribourg

Functional polymers through mechanochemistry

Schrettl, Stephen ; Balkenendea, Diederik W. R. ; Calvino, Céline ; Karman, Marc ; Lavrenova, Anna ; Neumann, Laura N. ; Sagaraa, Yoshimitsu ; Verde-Sestoa, Ester ; Giannantonio, Michela di ; Simon, Yoan C. ; Fromm, Katharina M. ; Lattuada, Marco ; Weder, Christoph

In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 7–11

While coupling mechanical and chemical processes is widespread in living organisms, the idea to harness the mechanically induced dissociation of weak covalent and non- covalent bonds to create artificial materials that respond to mechanical stimulation has only recently gained attention. Here we summarize our activities that mainly revolve around the exploitation of non-covalent interactions...

Université de Fribourg

Tautomerism in azo dyes: Border cases of azo and hydrazo tautomers as possible NMR reference compounds

Deneva, Vera ; Lyčka, Antonin ; Hristova, S. ; Crochet, Aurélien ; Fromm, Katharina M. ; Antonov, Liudmil M.

In: Dyes and Pigments, 2019, vol. 165, p. 157–163

In order to meet the need for NMR reference compounds in the study of tautomeric azo dyes, two series of azo dyes, derived from 3-methyl-1-phenyl-4- (phenyldiazenyl)-1H-pyrazol-5-amine and 5-methyl-2-phenyl-4-(2- phenylhydrazono)-2,4-dihydro-3H-pyrazol-3-one, have been studied by using molecular spectroscopy (UV–Vis and NMR) and quantum-chemical calculations (M06- 2X/TZVP) in solution. The...

Université de Fribourg

Synthesis and applications of nanocontainers and nanorattles

Abram, Sarah-Luise ; Yep, Philippe ; Fromm, Katharina M.

In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 12–16

Nanorattles and hollow nanocontainers have unique properties related to the presence of a void space inside the shell, which has been shown to improve the properties of materials for e.g. catalysis, drug release, sensor materials or lithium ion batteries. This article summarizes our recent progress in the synthesis of hollow silica, titania and ceria nanorattles and nanocontainers, eventually...

Université de Fribourg

Solid-state structure and anti­microbial and cytotoxicity studies of a cucurbit[6]uril-like Cu6L4 constructed from 3,5-bis­[(1H-tetra­zol-5-yl)meth­yl]-4H-1,2,4-triazol-4-amine

Vasylevskyi, Serhii ; Holzheu, Anja ; Fromm, Katharina M.

In: Acta Crystallographica Section C: Structural Chemistry, 2018, vol. 74, no. 11, p. 1413–1419

3,5-Bis[(1H-tetra­zol-5-yl)meth­yl]-4H-1,2,4-triazol-4-amine (H2L) associates under deprotonation with CuSO4 in aqueous medium to form a new waisted barrel-shaped M6L4 cluster, namely hexa­aqua­tetra­kis­{μ4-3,5-bis­[(1H-tetra­zol-5-yl)meth­yl]-4H-1,2,4- triazol-4-amine}-μ4-sulfato-hexa­copper(II) sulfate hydrate, [Cu6(SO4) (C6H6N12)4(H2O)6]SO4·nH2O (n = ∼23) (1). Cluster 1...

Université de Fribourg

Polyaspartamide functionalized catechol-based hydrogels embedded with silver nanoparticles for antimicrobial properties

Tan, Milène ; Choi, Youngjin ; Kim, Jaeyun ; Kim, Ji-Heung ; Fromm, Katharina M.

In: Polymers, 2018, vol. 10, no. 11, p. 1188

In this study, polyaspartamide-based hydrogels were synthesized by boron-catechol coordination followed by incorporation of AgNPs into the materials. Free catechol moieties were exploited to produce AgNPs. TEM analyses displayed AgNPs of less than 20 nm in diameter and with minimum aggregation, attesting the role of hydrogels to act as an efficient template for the production of dispersed...

Université de Fribourg

Betti bases from 4-(3-pyridazo)-1-naphthol: synthesis, coordination behaviour and unusual substitution reactions

Kurteva, Vanya B. ; Lubenov, Lubomir A. ; Shivachev, Boris L. ; Nikolova, Rositsa P. ; Fromm, Katharina M.

In: ChemistrySelect, 2018, vol. 3, no. 43, p. 12017–12021

A series of Betti bases from 4‐(3‐pyridyl)azo‐1‐naphthol dye, possessing flexible methylene or more constrained aryl‐methyne spaced NH‐containing side‐chains, were obtained and characterized. It was shown by NMR spectroscopy that the ligands exist in keto form. The products’ structure was confirmed by single crystal XRD of a selected sample. A study on the coordination ability...

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...