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Université de Fribourg

WRINKLED1 and ACYL‐COA:DIACYLGLYCEROL ACYLTRANSFERASE1 regulate tocochromanol metabolism in Arabidopsis

Pellaud, Sébastien ; Bory, Alexandre ; Chabert, Valentin ; Romanens, Joëlle ; Chaisse-Leal, Laurie ; Doan, Anh Vu ; Frey, Lucas ; Gust, Andrea ; Fromm, Katharina M. ; M?ne-Saffrané, Laurent

In: New Phytologist, 2018, vol. 217, no. 1, p. 245–260

Photosynthetic organisms such as plants, algae and some cyanobacteria synthesize tocochromanols, a group of compounds that encompasses tocopherols and tocotrienols and that exhibits vitamin E activity in animals. While most vitamin E biosynthetic genes have been identified in plant genomes, regulatory genes controlling tocopherol accumulation are currently unknown.We isolated by forward ...

Université de Fribourg

Versatile synthesis of chiral 6-oxoverdazyl radical ligands – new building blocks for multifunctional molecule-based magnets

Solea, Atena B. ; Wohlhauser, Tobie ; Abbasi, Parisa ; Mongbanziama, Yvan ; Crochet, Aurélien ; Fromm, Katharina M. ; Novitchi, Ghenadie ; Train, Cyrille ; Pilkington, Melanie ; Mamula, Olimpia

In: Dalton Transactions, 2018, vol. 47, no. 14, p. 4785–4789

A versatile synthetic methodology to access the first family of chiral verdazyl N,N′- chelate ligands is described and exemplified by N,N′-dimethyl-, N,N′-di-isopropyl- and N,N′-diphenyl oxoverdazyls bearing two isomers of the pinene-pyridine functional group. Their physical properties were probed by X-band EPR spectroscopy, cyclic voltammetry and DFT calculations. Preliminary...

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

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

Transport properties of solid state crown ether channel systems

Fromm, Katharina M. ; Bergougnant, Rémi D.

In: Solid State Sciences, 2007, vol. 9, no. 7, p. 580-587

Single crystals of [(H₂O)⊂(DB18C6)(μ₂-H₂O)2/2][(H₃O)⊂(DB18C6)(μ₂-H₂O)2/2]I₃ 1 were shown to possess ideally stacked crown ether molecules which form channels running in one direction through the solid state structure. By immersion of single crystals of 1 into NaOH, ion exchange takes place to yield the compound...

Université de Fribourg

A transparent, flexible, ion conductive, and luminescent PMMA ionogel based on a Pt/Eu bimetallic complex and the ionic liquid [Bmim][N(Tf)₂]

Xie, Zai-Lai ; Xu, Hai-Bing ; Geßner, André ; Kumke, Michael U. ; Priebe, Magdalena ; Fromm, Katharina M. ; Taubert, Andreas

In: Journal of Materials Chemistry, 2012, vol. 22, no. 16, p. 8110-8116

Transparent, ion-conducting, luminescent, and flexible ionogels based on the room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide [Bmim][N(Tf)₂], a PtEu₂ chromophore, and poly(methylmethacrylate) (PMMA) have been prepared. The thermal stability of the PMMA significantly increases with IL incorporation. In particular, the onset weight loss observed...

Université de Fribourg

Toxicity and protective effects of cerium oxide nanoparticles (Nanoceria) depending on their preparation method, particle size, cell type, and exposure route

Gagnon, Jacinthe ; Fromm, Katharina M.

In: European Journal of Inorganic Chemistry, 2015, vol. 2015, no. 27, p. 4510–4517

Nanoceria (cerium oxide nanoparticles) toxicity is currently a concern because of its use in motor vehicles in order to reduce carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons in exhaust gases. In addition, many questions arise with respect to its biomedical applications exploiting its potential to protect cells against irradiation and oxidative stress. Indeed, toxicology studies on...

Université de Fribourg

Towards cardiolite-inspired carbon monoxide releasing molecules – Reactivity of d4, d5 rhenium and d6 manganese carb­onyl complexes with isocyanide ligands

Kottelat, Emmanuel ; Chabert, Valentin ; Crochet, Aurélien ; Fromm, Katharina M. ; Zobi, Fabio

In: European Journal of Inorganic Chemistry, 2015, vol. 2015, no. 34, p. 5628–5638

Carbon monoxide releasing molecules (CORMs) are investigated widely in synthetic and medicinal chemistry owing to the potential therapeutic applications of the CO gas. Organometallic carbonyl complexes are best suited to play the role of CO carriers as they allow the exogenous release of CO under controlled conditions, and the toxicity of the gas can be overcome. With the long-term goal of...

Université de Fribourg

A Thermo‐ and mechanoresponsive cyano‐substituted oligo(p‐phenylene vinylene) derivative with five emissive states

Sagara, Yoshimitsu ; Lavrenova, Anna ; Crochet, Aurélien ; Simon, Yoan C. ; Fromm, Katharina M. ; Weder, Christoph

In: Chemistry - A European Journal, 2016, vol. 22, no. 13, p. 4374–4378

Multiresponsive materials that display predefined photoluminescence color changes upon exposure to different stimuli are attractive candidates for advanced sensing schemes. Herein, we report a cyano-substituted oligo(p-phenylene vinylene) (cyano-OPV) derivative that forms five different solvent-free solid-state molecular assemblies, luminescence properties of which change upon thermal and...

Université de Fribourg

On the coordination behaviour of NO₃⁻ in coordination compounds with Ag⁺Part 1. Solubility effect on the formation of coordination polymer networks between AgNO₃ and L(L= ethanediyl bis(isonicotinate) as a function of solvent

Robin, Adeline Y. ; Sagué, Jorge L. ; Fromm, Katharina M.

In: CrystEngComm, 2006, vol. 8, p. 403-416

The influence of the solubility of AgNO₃ in three solvent systems is studied for the reaction between AgNO₃ and the ligand L(= ethanediyl bis(isonicotinate)). Three solid state structures are obtained, differing in the relative ratio Ag : L in the first case, and in polymorphism in the second. The Ag–O(NO₃⁻) distance correlates strongly with the solubility of AgNO₃ in...