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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...

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...