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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, Aurelien ; 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

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

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...

Université de Fribourg

The first phospho­ramide-mercury(II) complex with a Cl₂Hg-OP[N(C)(C)]₃ segment

Saneei, Anahid ; Pourayoubi, Mehrdad ; Crochet, Aurelien ; Fromm, Katharina M.

In: Acta Crystallographica C, 2016, vol. 72, p. 230-233

Mercury(II) exhibits a strong preference for linear coordination which has been attributed to relativistic effects splitting the 6p orbitals and promoting sp hybridization. If the two ligands attached to the mercury(II) ion are weak donors, the metal ion can act as a good Lewis acid and expand its coordination number. Moreover, mercury has a special affinity for softer bases,...

Université de Fribourg

Controlled tautomeric switching in azonaphthols tuned by substituents on the phenyl ring

Antonov, Liudmil ; Deneva, Vera ; Simeonov, Svilen ; Kurteva, Vanya ; Crochet, Aurelien ; Fromm, Katharina M. ; Shivachev, Boris ; Nikolova, Rositsa ; Savarese, Marika ; Adamo, Carlo

In: ChemPhysChem, 2015, vol. 16, no. 3, p. 649–657

A series of new tautomeric azonaphthols are synthesized and the possibilities for molecular switching are investigated using molecular spectroscopy, X-ray analysis and density functional theory quantum chemical calculations. Two opposite effects that influence switching are studied: attaching a piperidine sidearm, and adding substituents to the phenyl ring. On the one hand, the attached...

Université de Fribourg

Cis-Dioxido-molybdenum(VI) complexes of tridentate ONO hydrazone Schiff base: Synthesis, characterization, X-ray crystal structure, DFT calculation and catalytic activity

Ebrahimipour, S. Yousef ; Khabazadeh, , , Hojatollah ; Castro, Jesús ; Sheikhshoaie, Iran ; Crochet, Aurelien ; Fromm, Katharina M.

In: Inorganica Chimica Acta, 2015, vol. 427, p. 52–61

Two new cis-MoO₂ [MoO₂(L)(EtOH)] (1), [MoO₂(L)(Py)] (2) [L: (3-methoxy-2oxidobenzylidene)benzohydrazidato], complexes have been synthesized and fully characterized on the basis of elemental analysis, FT-IR, molar conductivity, ¹H NMR, ¹³C NMR and electronic spectra. The structure of complexes has been accomplished by single crystal X-ray...

Université de Fribourg

A new mixed-ligand copper(II) complex of (E)-N′-(2-hydroxybenzylidene) acetohydrazide: Synthesis, characterization, NLO behavior, DFT calculation and biological activities

Ebrahimipour, S. Yousef ; Sheikhshoaie, Iran ; Crochet, Aurelien ; Khaleghi, Moj ; Fromm, Katharina M.

In: Journal of Molecular Structure, 2014, vol. 1072, p. 267–276

A tridentate hydrazone Schiff base ligand, (E)-N′-(2-hydroxybenzylidene)acetohydrazide [HL], and its mixed-ligand Cu(II) complex [CuL(phen)], have been synthesized and characterized by elemental analyses, FT-IR, molar conductivity, UV–Vis spectroscopy. The structure of the complex has been determined by X-ray diffraction. This complex has square pyramidal geometry and the positions around...

Université de Fribourg

Crystallography for university research: some basic case studies

Crochet, Aurelien

In: CHIMIA International Journal for Chemistry, 2014, vol. 68, no. 5, p. 325–328

An overview of commonly available, state-of-the-art diffraction techniques for university research is presented based on some chemical case studies. Examples from the Fribourg crystallography service are presented, aimed at scientists who would like to learn about the principal possibilities that X-ray powder and single-crystal diffraction can offer, how these methods can serve to determine the...

Université de Fribourg

Polymorphism, what it is and how to identify it: a systematic review

Brog, Jean-Pierre ; Chanez, Claire-Lise ; Crochet, Aurelien ; Fromm, Katharina M.

In: RSC Advances, 2013, vol. 3, no. 38, p. 16905–16931

This review on polymorphism is a personal, non-comprehensive view on the field of polymorphism – a term which is often misused. Indeed, the discussion about polymorphism and related terms is still ongoing in the area of crystal engineering. This is why we felt it timely to look into the historical development of its definition and to delimit it. A short introduction to thermodynamic aspects and...