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Université de Fribourg

Influence of anions and solvent molecules on the packing and emission spectra of coordination polymers based on silver ions and an anthracene derivative

Chen, Jing ; Voutier, Noémie ; Rajabi, Jamshid ; Crochet, Aurélien ; Bassani, Dario M. ; Fromm, Katharina M.

In: CrystEngComm, 2017, vol. 19, no. 34, p. 5106–5113

Luminescence between green and blue was observed in the solid state for the free ligand L (anthracene-9,10-diylbis(methylene) dinicotinate) and five different Ag-L coordination polymers upon excitation at 344 nm. Depending on the packing of the anthracene moieties due to coordinating anions and the presence or absence of solvent molecules, the emission maximum is shifted.

Université de Fribourg

Characteristics and properties of nano-LiCoO2 synthesized by pre-organized single source precursors: Li-ion diffusivity, electrochemistry and biological assessment

Brog, Jean?Pierre ; Crochet, Aurélien ; Seydoux, Joël ; Clift, Martin J. D. ; Baichette, Benoît ; Maharajan, Sivarajakumar ; Barosova, Hana ; Brodard, Pierre ; Spodaryk, Mariana ; Züttel, Andreas ; Rothen?Rutishauser, Barbara ; Kwon, Nam Hee ; Fromm, Katharina M.

In: Journal of Nanobiotechnology, 2017, vol. 15, p. 58

LiCoO₂ is one of the most used cathode materials in Li-ion batteries. Its conventional synthesis requires high temperature (>800 °C) and long heating time (>24 h) to obtain the micronscale rhombohedral layered high-temperature phase of LiCoO₂ (HT-LCO). Nanoscale HT-LCO is of interest to improve the battery performance as the lithium (Li⁺) ion pathway is expected to be shorter in...

Université de Fribourg

Influence of the sacrificial polystyrene removal pathway on the TiO₂ nanocapsule structure

Hérault, Nelly ; Fromm, Katharina M.

In: Helvetica Chimica Acta, 2017, vol. 100, no. 6, p. -

This study demonstrates the significant influence of the polystyrene removal pathway on the TiO₂ nanocapsules obtained from PS@TiO₂ core-shell particles. In a first step, the polystyrene spheres were coated with titanium oxide via hydrolysis and condensation of the titanium precursor to form PS@TiO₂ core-shell particles. Then, the creation of the empty cavity to form TiO₂ nanocapsules was...

Université de Fribourg

Model peptide studies of Ag+ binding sites from the silver resistance protein SilE

Chabert, Valentin ; Hologne, M. ; Sénèque, O. ; Crochet, Aurélien ; Walker, O. ; Fromm, Katharina M.

In: Chemical Communications, 2017, vol. 53, no. 45, p. 6105–6108

Using model peptides, each of the nine MX2H or HXnM (n = 1, 2) motifs of the silver resistance protein SilE has been shown to coordinate to one Ag+ ion by its histidine and methionine residues with Kd in the μM range. This suggests an Ag+ buffering role for SilE in the case of high Ag+ overload.

Université de Fribourg

Heptacoordinate Coii complex: a new architecture for photochemical hydrogen production

Lucarini, Fiorella ; Pastore, Mariachiara ; Vasylevskyi, Serhii ; Varisco, Massimo ; Solari, Euro ; Crochet, Aurelien ; Fromm, Katharina M. ; Zobi, Fabio ; Ruggi, Albert

In: Chemistry - A European Journal, 2017, p. -

The first heptacoordinate cobalt catalyst for light-driven hydrogen production in water has been synthesized and characterized. Photochemical experiments using [Ru(bpy)₃]²⁺ as photosensitizer gave a turnover number (TON) of 16300 mol H₂ (mol cat.)⁻¹ achieved in 2 hours of irradiation with visible (475 nm) light. This promising result provides a path forward in the...

Université de Fribourg

Nanoparticle shapes of LiMnPO4, Li+ diffusion orientation and diffusion coefficients for high volumetric energy Li+ ion cathodes

Kwon, Nam Hee ; Yin, , Hui ; Vavrova, Tatiana ; Lim, Jonathan H-W. ; Steiner, Ullrich ; Grobéty, Bernard ; Fromm, Katharina M.

In: Journal of Power Sources, 2017, vol. 342, p. 231–240

Nanoparticles of LiMnPO₄ were fabricated in rod, elongated as well as cubic shapes. The 1D Li⁺ preferred diffusion direction for each shape was determined via electron diffraction spot patterns. The shape of nano-LiMnPO₄ varied the diffusion coefficient of Li⁺ because the Li⁺ diffusion direction and the path length were different. The particles with the shortest dimension along the...

Université de Fribourg

Formation of silver nanoparticles by electron transfer in peptides and c‐cytochromes

Vasylevskyi, Serhii I. ; Kracht, Sonja ; Corcosa, Paula ; Fromm, Katharina M. ; Giese, Bernd ; Füeg, Michael

In: Angewandte Chemie International Edition, 2017, p. -

The reduction of Ag⁺ ions to Ag⁰ atoms is a highly endergonic reaction step, only the aggregation to Agn clusters leads to an exergonic process. These elementary chemical reactions play a decisive role if Ag nanoparticles (AgNPs) are generated by electron transfer (ET) reactions to Ag⁺ ions. We studied the formation of AgNPs in peptides by photoinduced ET, and in...

Université de Fribourg

Antimicrobial silver-filled silica nanorattles with low immunotoxicity in dendritic cells

Priebe, Magdalena ; Widmer, Jérôme ; Löwa, Nina Suhartha ; Abram, Sarah-Luise ; Mottas, Inès ; Woischnig, Anne-Kathrin ; Brunetto, Priscilla S. ; Khanna, Nina ; Bourquin, Carole ; Fromm, Katharina M.

In: Nanomedicine: Nanotechnology, Biology and Medicine, 2017, vol. 13, no. 1, p. 11–22

The progression in the use of orthopedic implants has led to an increase in the absolute number of implant infections, triggering a search for more effective antibacterial coatings. Nanorattles have recently gained interest in biomedical applications such as drug delivery, as encapsulation of the cargo inside the hollow structure provides a physical protection from the surrounding...

Université de Fribourg

Tandem ring‐opening–ring‐closing metathesis for functional metathesis catalysts

Nagarkar, Amit A. ; Yasir, Mohammad ; Crochet, Aurelien ; Fromm, Katharina M. ; Kilbinger, Andreas F. M.

In: Angewandte Chemie International Edition, 2016, vol. 55, no. 40, p. 12343–12346

Use of a tandem ring-opening–ring-closing metathesis (RORCM) strategy for the synthesis of functional metathesis catalysts is reported. Ring opening of 7-substituted norbornenes and subsequent ring-closing metathesis forming a thermodynamically stable 6-membered ring lead to a very efficient synthesis of new catalysts from commercially available Grubbs’ catalysts. Hydroxy functionalized...