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Université de Fribourg

Real- and Q-space travelling: multi-dimensional distribution maps of crystal-lattice strain (∊044) and tilt of suspended monolithic silicon nanowire structures

Dolabella, Simone ; Frison, Ruggero ; Chahine, Gilbert A. ; Richter, Carsten ; Schulli, Tobias U. ; Tasdemir, Zuhal ; Alaca, B. Erdem ; Leblebic, Yusuf ; Dommann, Alex ; Neels, Antonia

In: Journal of Applied Crystallography, 2020, vol. 53, no. 1, p. 58–68

Silicon nanowire-based sensors find many applications in micro- and nano- electromechanical systems, thanks to their unique characteristics of flexibility and strength that emerge at the nanoscale. This work is the first study of this class of micro- and nano-fabricated silicon-based structures adopting the scanning X-ray diffraction microscopy technique for mapping the in-plane crystalline...

Université de Fribourg

Structural insights into semicrystalline states of electrospun nanofibers: a multiscale analytical approach

Maurya, Anjani K. ; Weidenbacher, Lukas ; Spano, Fabrizio ; Fortunato, Giuseppino ; Rossi, René M. ; Frenz, Martin ; Dommann, Alex ; Neels, Antonia ; Sadeghpour, Amin

In: Nanoscale, 2019, vol. 11, no. 15, p. 7176–7187

A dedicated nanofiber design for applications in the biomedical domain is based on the understanding of nanofiber structures. The structure of electrospun nanofibers strongly influences their properties and functionalities. In polymeric nanofibers X-ray scattering and diffraction methods, i.e. SAXS and WAXD, are capable of decoding their structural insights from about 100 nm down to the...

Université de Fribourg

Probing intermetallic coupling in dinuclear N-heterocyclic carbene ruthenium(II) complexes

Mercs, Laszlo ; Neels, Antonia ; Stoeckli-Evans, Helen ; Albrecht, Martin

In: Inorganic Chemistry, 2011, vol. 50, no. 17, p. 8188–8196

A series of bimetallic N-heterocyclic carbene (NHC) ruthenium(II) complexes were synthesized, which comprise two [RuCl₂(cymene)(NHC)] units that are interlinked via the NHC nitrogens by alkyl chains of different length. Electrochemical characterization revealed two mutually dependent oxidation processes for the complex with a methylene linker, indicating moderate intramolecular electronic...

Université de Fribourg

Chelating C4-bound imidazolylidene complexes through oxidative addition of imidazolium salts to palladium(0)

Krüger, Anneke ; Kluser, Evelyne ; Müller-Bunz, Helge ; Neels, Antonia ; Albrecht, Martin

In: European Journal of Inorganic Chemistry, 2012, p. -

Oxidative addition of donor-functionalised 4-iodoimidazolium salts to palladium(0) provides a selective route for the preparation of abnormal chelating N-heterocyclic carbene complexes and enables the introduction of a variety of donor groups. The activation of the C4 position does not necessitate protection of the imidazolium C2 position, thereby leaving this site available for further...

Université de Fribourg

Synthesis and tunability of abnormal 1,2,3-triazolylidene palladium and rhodium complexes

Poulain, Aurélie ; Canseco-Gonzalez, Daniel ; Hynes-Roche, Rachel ; Müller-Bunz, Helge ; Schuster, Oliver ; Stoeckli-Evans, Helen ; Neels, Antonia ; Albrecht, Martin

In: Organometallics, 2011, vol. 30, no. 5, p. 1021–1029

Palladation of N3-alkylated 1,2,3-triazolium salts with Pd(OAc)₂ afforded a μ²−I₂ bridged bimetallic complex [Pd(trz)I₂]₂ and monometallic bis(carbene) complexes Pd(trz)₂I₂ as a mixture of trans and cis isomers (trz = 1,2,3-triazol-5- ylidene). Addition of excess halide or modification of the palladation procedure from direct functionalization to a transmetalation...

Université de Fribourg

Catalytic hydrogenation using abnormal N-heterocyclic carbene palladium complexes: catalytic scope and mechanistic insights

Heckenroth, Marion ; Khlebnikov, Vsevolod ; Neels, Antonia ; Schurtenberger, Peter ; Albrecht, Martin

In: ChemCatChem, 2011, vol. 3, no. 1, p. 167-173

Palladium complexes containing abnormally bound C4-bound dicarbene ligands have been exploited for catalytic alkene hydrogenation. Comparison to normally C2-bound homologues indicates that the carbene bonding mode critically influences the catalytic activity. Good catalytic performance in the hydrogenation of cis-disubstituted olefins and non-isomerizable terminal olefins under mild...

Université de Fribourg

Main-chain organometallic polymers comprising redox-active iron(II) centers connected by ditopic N-heterocyclic carbenes

Mercs, Laszlo ; Neels, Antonia ; Stoeckli-Evans, Helen ; Albrecht, Martin

In: Dalton Transactions, 2009, vol. 35, p. 7168-7178

Main-chain organometallic polymers were synthesized from bimetallic iron(II) complexes containing a ditopic N-heterocyclic carbene (NHC) ligand [(cp)(CO)LFe(NHC∼NHC)Fe(cp)(CO)L]X₂ (where NHC∼NHC represents a bridging dicarbene ligand, L = I⁻ or CO). Addition of a diimine ligand such as pyrazine or 4,4′-bipyridine, interconnected these bimetallic complexes and gave 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

On the electronic impact of abnormal C4-bonding in N-heterocyclic carbene complexes

Heckenroth, Marion ; Neels, Antonia ; Garnier, Michael G. ; Aebi, Philipp ; Ehlers, Andreas W. ; Albrecht, Martin

In: Chemistry - A European Journal, 2009///doi: 10.1002/chem.200900249

Sterically similar palladium dicarbene complexes have been synthesized that comprise permethylated dicarbene ligands which bind the metal center either in a normal coordination mode via C2 or abnormally via C4. Due to the strong structural analogy of the complexes, differences in reactivity patterns may be attributed to the distinct electronic impact of normal versus abnormal carbene bonding,...