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Université de Fribourg

4-Hydroxy-1-naphthaldehydes: proton transfer or deprotonation

Manolova, Y. ; Kurteva, Vanya B. ; Antonov, Liudmil M. ; Marciniak, H. ; Lochbrunner, S. ; Crochet, Aurélien ; Fromm, Katharina M. ; Kamounah, Fadhil S. ; Hansen, P. E.

In: Physical Chemistry Chemical Physics, 2015, vol. 17, no. 15, p. 10238–10249

A series of naphthaldehydes, including a Mannich base, have been investigated by UV-Vis spectroscopy, NMR and theoretical methods to explore their potential tautomerism. In the case of 4-hydroxy-1-naphthaldehyde concentration dependent deprotonation has been detected in methanol and acetonitrile. For 4-hydroxy-3-(piperidin-1-ylmethyl)-1-naphthaldehyde (a Mannich base) an intramolecular proton...

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

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

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...

Université de Fribourg

Amino acids in iron oxide mineralization: (incomplete) crystal phase selection is achieved even with single amino acids

Mantion, Alexandre ; Gozzo, Fabia ; Schmitt, Bernd ; Stern, Willem B. ; Gerber, Yvonne ; Robin, Adeline Y. ; Fromm, Katharina M. ; Painsi, Monika ; Taubert, Andreas

In: The Journal of Physical Chemistry C, 2008, vol. 112, no. 32, p. 12104–12110

Iron oxides are important minerals in biology and materials science. Using biomimetic synthesis, a variety of iron oxides have been fabricated. However, it is still not clear how growth modifiers like amino acids and peptides select different crystal phases of a complex material like iron oxide. The current paper shows that already with single amino acids, (incomplete) crystal phase selection is...

Université de Fribourg

Analogy of the Coordination Chemistry of Alkaline Earth Metal and Lanthanide Ln²⁺ Ions: The Isostructural Zoo of Mixed Metal Cages [IM(OtBu)₄{Li(thf)}₄(OH)] (M=Ca, Sr, Ba, Eu), [MM′₆(OPh)₈(thf)₆] (M=Ca, Sr, Ba, Sm, Eu, M′=Li, Na), and their Derivatives with 1,2-Dimethoxyethane

Maudez, William ; Meuwly, Markus ; Fromm, Katharina M.

In: Chemistry - A European Journal, 2007, vol. 13, no. 29, p. 8302 - 8316

As previously shown, alkali and alkaline earth metal iodides in nonaqueous, aprotic solvents behave like transition metal halides, forming cis- and trans-dihalides with various neutral O-donor ligands. These compounds can be used as precursors for the synthesis of new mixed alkali/alkaline earth metal aggregates. We show here that Ln²⁺ ions form isostructural cluster compounds....

Université de Fribourg

Anion-induced structural diversity of Zn and Cd coordination polymers based on bis-9,10-(pyridine-4-yl)-anthracene, their luminescent properties, and highly efficient sensing of nitro derivatives and herbicides

Vasylevskyi, Serhii I. ; Bassani, Dario M. ; Fromm, Katharina M.

In: Inorganic Chemistry, 2019, vol. 58, no. 9, p. 5646–5653

Luminescent coordination polymers (CPs) of Zn2+ or Cd2+ and bis-9,10-(pyridine-4- yl)-anthracene (BA) show different 1D and 2D topologies depending on the anion used in the precursor. Compounds {[Zn(μ2-BA)(MeOH)2(p-Tos)2]}n (1) and {[Zn(μ2- BA)(MeOH)2(CF3CO2)2]}n (2) form linear structures and {BA@[Zn(μ2-BA) (MeOH)2(H2O)2](CF3SO3)2}n (3) featuring intercalation of uncoordinated BA molecules...

Université de Fribourg

Antimicrobial coatings for implant surfaces

Brunetto, Priscilla S. ; Fromm, Katharina M.

In: Chimia, 2008, vol. 62, no. 4, p. 249-252

Body-foreign materials are used more and more frequently in our lives: joint implants (hips, knees, fingers, etc.), catheters, pacemakers, dental and aesthetic implants, etc. The increasing numbers of patients requiring such implants also raises the absolute numbers of implant-related infections. Thus, it is known that body-foreign materials are prone to bacterial adhesion and subsequent biofilm...

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

Bimetallic salen-based compounds and their potential applications

Finelli, Alba ; Abram, Sarah-Luise ; Hérault, Nelly ; Crochet, Aurélien ; Fromm, Katharina M.

In: Crystal Growth & Design, 2020, vol. 20, no. 8, p. 4945–4958

The new bimetallic coordination compounds [LNiAg(NO3)], [LCuMn(NO3)2], [LCuCu(NO3)2], [LCuZn(NO3)2], and [{LCuBi(NO3)3}(ACN)] have been synthesized from a salen-type ligand L containing two distinct coordination sites to accommodate (different) metal ions M1 and M2. In the solid state, the formation of 1:1 compounds (LCu:M2) is always observed, but interactions between the compounds lead to ...