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Université de Fribourg

Synthesis, X-ray structure and DFT calculation of oxido-vanadium(V) complex with a tridentate Schiff base ligand

Sheikhshoaie, Iran ; Ebrahimipour, S. Yousef ; Crochet, Aurélien ; Fromm, Katharina M.

In: Research on Chemical Intermediates, 2015, vol. 41, no. 4, p. 1881–1891

Reaction of 4-bromo-2-(((5-chloro-2-hydroxyphenyl) imino)methyl)phenol (H₂L) with VOSO₄·XH₂O generates the oxido-vanadium(V) complex [VOL(OCH₃)(OHCH₃)], that characterized by FT-IR, UV–Vis, and elemental analysis. The complex was also characterized by single crystal X-ray diffraction crystallography. A DFT calculation was carried out on the complex using the B3LYP/6-31+G(d,p) method....

Université de Fribourg

Integrating silver compounds and nanoparticles into ceria nanocontainers for antimicrobial applications

Gagnon, Jacinthe ; Clift, Martin J. D. ; Vanhecke, Dimitri ; Kuhn, Dagmar Alice ; Weber, P. ; Petri-Fink, Alke ; Rothen-Rutishauser, Barbara ; Fromm, Katharina M.

In: Journal of Materials Chemistry B, 2015, vol. 3, no. 9, p. 1760–1768

Silver compounds and nanoparticles (NPs) are gaining increasing interest in medical applications, specifically in the treatment and prevention of biomaterial-related infections. However, the silver release from these materials, resulting in a limited antimicrobial activity, is often difficult to control. In this paper, ceria nanocontainers were synthesized by a template-assisted method and were...

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

The influence of dipole moments on the mechanism of electron transfer through helical peptides

Lauz, Miriam ; Eckhardt, Sonja ; Fromm, Katharina M. ; Giese, Bernd

In: Physical Chemistry Chemical Physics, 2012, vol. 14, no. 40, p. 13785-13788

The life time of aromatic radical cations is limited by reactions like β-elimination, dimerization, and addition to the solvent. Here we show that the attachment of such a radical cation to the C-terminal end of an α-/3₁₀-helical peptide further reduces its life time by two orders of magnitude. For PPII-helical peptides, such an effect is only observed if the peptide contains an adjacent...

Université de Fribourg

Antibacterial properties of nanoparticles

Hajipour, Mohammad J. ; Fromm, Katharina M. ; Ashkarran, Ali Akbar ; Aberasturi, Dorleta Jimenez de ; Larramendi, Idoia Ruiz de ; Rojo, Teofilo ; Serpooshan, Vahid ; Parak, Wolfgang J. ; Mahmoudi, Morteza

In: Trends in Biotechnology, 2012, p. -

Antibacterial agents are very important in the textile industry, water disinfection, medicine, and food packaging. Organic compounds used for disinfection have some disadvantages, including toxicity to the human body, therefore, the interest in inorganic disinfectants such as metal oxide nanoparticles (NPs) is increasing. This review focuses on the properties and applications of inorganic...

Université de Fribourg

Preparation of imidazolidin-4-ones and their evaluation as hydrolytically cleavable precursors for the slow release of bioactive volatile carbonyl derivatives

Trachsel, Alain ; Buchs, Barbara ; Godin, Guillaume ; Crochet, Aurélien ; Fromm, Katharina M. ; Herrmann, Andreas

In: European Journal of Organic Chemistry, 2012, no. 14, p. 2837–2854

Imidazolidin-4-ones are suitable in practical applications as hydrolytically cleavable precursors for the controlled release of fragrant aldehydes and ketones. The corresponding profragrances were prepared by treating aliphatic carbonyl compounds with commercially available amino acid amines in the presence of a base to yield mixtures of diastereomers. The two diastereomers isolated from the...

Université de Fribourg

Effect of increasing ligand length on the structure of silver complexes

Gschwind, Fabienne ; Fromm, Katharina M.

In: CrystEngComm, 2012, p. -

A new series of ligands in which nicotinic acid was linked to different monomethyloligoethers and their corresponding silver complexes were prepared. The crystal structures of the silver compounds were investigated to determine the effect of increasing flexibility of the ligands on coordination to the metal ion and crystal packing. We observed the formation of one-dimensional coordination...

Université de Fribourg

Enhanced electrochemical performance of <30 nm thin LiMnPO4 nanorods with a reduced amount of carbon as a cathode for lithium ion batteries

Kwon, Nam Hee ; Fromm, Katharina M.

In: Electrochimica Acta, 2012, vol. 69, p. 38-44

5–10 nm thin rod shaped LiMnPO₄ nanoparticles are synthesized by an improved thermal decomposition method. The synthesis parameters such as the concentration of surfactants, reaction temperature and time, as well as the presence of a solvent play a critical role in the formation of spherical, thin or thick nanorods, and needle-shaped particles of LiMnPO₄. A washing procedure to efficiently...

Université de Fribourg

Coordination Networks of Mercury(II) Halides and Polyether Ligand

Crochet, Aurélien ; Fromm, Katharina M.

In: Zeitschrift für anorganische und allgemeine Chemie, 2011, vol. 637, no. 14-15, p. 2089–2092

New crystalline mercury halide adducts with polyetheras ligands were isolated, characterized, and identified as trans-[HgIICl₂(diox)₂]n (1) and trans-[HgIII₂(diox)]n (2). The compounds were obtained from the metal halide salts in solution of 1,4-dioxane and can be considered as “cutting-out”...

Université de Fribourg

Tetraethylene glycol adducts of alkaline earth halides

Gschwind, Fabienne ; Fromm, Katharina M.

In: Zeitschrift für anorganische und allgemeine Chemie, 2011, vol. 637, no. 12, p. 1871–1879

Reaction of commercially available tetraethylene glycol with different alkaline earth metal halides affords tetraethylene glycol complexes with different coordination numbers at the metal ion and structural features; depending on the ionic radius of the metal ion, one or two ligand molecules will be coordinated to the metal ion. In this article we will first present complexes with...