Université de Fribourg

A magnetic iron(III) switch with controlled and adjustable thermal response for solution processing

Gandolfi, Claudio ; Morgan, Grace G. ; Albrecht, Martin

In: Dalton Transactions, 2012, vol. 41, no. 13, p. 3726-3730

Spin crossover requires cooperative behavior of the metal centers in order to become useful for devices. While cooperativity is barely predictable in solids, we show here that solution processing and the covalent introduction of molecular recognition sites allows the spin crossover of iron(III) sal₂trien complexes to be rationally tuned. A simple correlation between the number of molecular...

Université de Fribourg

Modulating the steric, electronic, and catalytic properties of cp* ruthenium half-Sandwich complexes with β-diketiminato ligands

Phillips, Andrew D. ; Thommes, Katrin ; Scopelliti, Rosario ; Gandolfi, Claudio ; Albrecht, Martin ; Severin, Kay ; Schreiber, Dominique F. ; Dyson, Paul J.

In: Organometallics, 2011, vol. 30, no. 22, p. 6119–6132

Five different types of β-diketiminate ligands, bearing electron-donating to strongly electron-withdrawing substituents, were synthesized and used in the synthesis of Cp* ruthenium complexes (Cp* = η⁵-C₅Me₅). One series consists of complexes with a covalent RuIII–Cl bond, and the other series features a reduced RuII center, where the chloride is abstracted by...

Université de Fribourg

Transfer hydrogenation of ketones and activated olefins using chelating NHC ruthenium complexes

Horn, Sabine ; Gandolfi, Claudio ; Albrecht, Martin

In: European Journal of Inorganic Chemistry, 2011, vol. 2011, no. 18, p. 2863–2868

N-Heterocyclic carbene (NHC) ruthenium complexes consisting of different donor substituents attached to the NHC ligand efficiently catalyse the transfer hydrogenation of ketones and of activated olefins in α,β-unsaturated ketones to give saturated alcohols. The most active catalyst precursor contains a tethered olefin as a hemilabile donor site. This complex also converts nitriles and,...

Université de Fribourg

Room-temperature spin crossover and Langmuir–Blodgett film formation of an iron(II) triazole complex featuring a long alkyl chain substituent: the tail that wags the dog

Kitchen, Jonathan A. ; White, Nicholas G. ; Gandolfi, Claudio ; Albrecht, Martin ; Jameson, Guy N. L. ; Tallon, Jeffery L. ; Brooker, Sally

In: Chemical Communications, 2010, vol. 46, no. 35, p. 6464-6466

[FeII(C₁₆dpt)₂(NCS)₂]·⅔H₂O displays temperature-mediated spin crossover (SCO) with T½ = 290 K and the long alkyl chain substituent on the dipyridyltriazole ligand facilitates the formation of a stable Langmuir–Blodgett film at an air–water interface.

Université de Fribourg

Organization of spin- and redox-labile metal centers into Langmuir and Langmuir–Blodgett films

Gandolfi, Claudio ; Miyashita, Naoko ; Kurth, Dirk G. ; Martinho, Paulo N. ; Morgan, Grace G. ; Albrecht, Martin

In: Dalton Transactions, 2010, vol. 39, p. 4508-4516

New sal₂(trien) ligands that contain alkoxy substituents of various length in meta position of the phenolate entities were coordinated to electronically and magnetically active iron(III) and cobalt(III) centers. The electrochemical and spectroscopic properties of these amphiphilic complexes are virtually unaffected upon alteration of the alkoxy substituents, thus providing a system...

Université de Fribourg

Towards Langmuir–Blodgett films of magnetically interesting materials: solution equilibria in amphiphilic iron(II) complexes of a triazole-containing ligand

White, Nicholas G. ; Feltham, Humphrey L. C. ; Gandolfi, Claudio ; Albrecht, Martin ; Brooker, Sally

In: Dalton Transactions, 2010, vol. 39, p. 3751-3758

As a first step towards amphiphilic spin crossover (SCO) systems where the hydrophobic part of the system is introduced by a non-coordinating anion (i.e. where no modification of the ligands to introduce hydrophobic substituents is required), [FeII(OH₂)₂(C₁₆SO₃)₂] and [CoII(OH₂)₂(C₁₆SO₃)₂] have been prepared and reacted with the...

Université de Fribourg

Chelating NHC ruthenium(II) complexes as robust homogeneous hydrogenation catalysts

Gandolfi, Claudio ; Heckenroth, Marion ; Neels, Antonia ; Laurenczy, Gbor ; Albrecht, Martin

In: Organometallics, 2009, vol. 28, no. 17, p. 5112–5121

A series of ruthenium(II) complexes have been prepared by using bidentate chelating N-heterocyclic carbene (NHC) ligands that feature different donor groups E (E = olefin, thioether, carboxylate, and NHC). Rigid coordination of all donor sites was concluded from NMR spectroscopy, and the electronic impact of the donor group was evaluated by electrochemical analyses. The chelating donor group had...

Université de Fribourg

Improved cooperativity of spin-Labile iron(III) centers by self-assembly in solution

Gandolfi, Claudio ; Moitzi, Christian ; Schurtenberger, Peter ; Morgan, Grace G. ; Albrecht, Martin

In: Journal of the American Chemical Society, 2008, vol. 130, no. 44, p. 14434–14435

Supramolecular principles have been applied for improving the spin crossover activity of metal centers due to cooperative effects in solution. Thus, incorporation of alkyloxy tails at the phenyl group of Fe(sal₂trien) 2a provides amphiphilic complexes Fe(sal-OR₂trien) 2b−d (b, R = C₆H₁₃; c, R = C₈H₁₇; d, R = C₁₈H₃₇) comprising an apolar...