Université de Fribourg

Tautomerism and self-association in the solution of new pinene-bipyridine and pinene-phenanthroline derivatives

Solea, Atena B. ; Cornu, Ivan ; Deneva, Vera ; Crochet, Aurélien ; Fromm, Katharina M. ; Antonov, Liudmil ; Allemann, Christophe ; Mamula, Olimpia

In: Molecules, 2020, vol. 25, no. 2, p. 298

Two novel pinene-type ligands have been synthesized and their tautomeric and self- associating behavior studied in solution and in the solid state. The first ligand, an acetylated derivative of 5,6-pinene-bipyridine, displays keto-enol tautomerism in solution. This tautomeric equilibrium was studied by NMR and UV-Vis spectroscopy in various solvents, and the results were compared with the ones...

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

Self-assembly of Ag(I) helicates with new enantiopure 5,6-Chiragen type ligands

Mamula, Olimpia ; Bark, Thomas ; Quinodoz, Boris ; Stoeckli-Evans, Helen ; Zelewsky, Alexvon

In: Inorganica Chimica Acta, 2018, vol. 475, p. 200–206

Two new chiral bis-bidentate, C2-symmetrical ligands belonging to the Chiragen family have been synthesised and characterised. They are designed for polynuclear self-assemblies since the two (−)-5,6-pinenebipyridines units are connected by bridges whose length and rigidity avoids the coordination of the bipyridine moieties to the same metal centre. The ligand L1 with a 1,4-dimethylene...

Université de Fribourg

Synthesis of hydrophilic and hydrophobic carbon quantum dots from waste of wine fermentation

Varisco, Massimo ; Zufferey, Denis ; Ruggi, Albert ; Zhang, Yucheng ; Erni, Rolf ; Mamula, Olimpia

In: Royal Society Open Science, 2017, vol. 4, no. 12, p. 170900

Wine lees are one of the main residues formed in vast quantities during the fermentation of wine. While toxic when applied to plants and wetlands, it is a biodegradable material, and several alternatives have been proposed for its valorization as: dietary supplement in animal feed, source for various yeast extracts and bioconversion feedstock. The implementation of stricter environment...

Université de Fribourg

A family of immobilizable chiral bis(pinenebipyridine) ligands

Pöllnitz, Alpár ; Skupienski, Radek ; Stoeckli-Evans, Helen ; Crochet, Aurélien ; Silvestru, Anca ; Fromm, Katharina M. ; Mamula, Olimpia

In: Synlett, 2013, vol. 24, no. 19, p. 2555–2558

New enantiopure ligands containing two (–)-5,6-pinenebipyridine units connected by a bridge situated in position 6′ of the bipyridines have been prepared. The chemically addressable groups of the bridging (hydroxyl or keto) can be covalently bound to various supports in order to heterogenize the ligand.