Units

High Resolution Nuclear Magnetic Resonance

The High-Resolution NMR lab, headed by Prof. Michel Luhmer, is part of the “Service de Chimie et PhysicoChimie Organiques". The research focusses on the development and applications of multinuclear solution-state NMR spectroscopy in the framework of structural, thermodynamic, kinetic and/or dynamic studies and deals with a large variety of systems.
Major current research topics are (i) the characterization of supramolecular assemblies, (ii) the study of photochemical processes and, more recently, (iii) the characterization of electrochemical processes. A major achievement is the development of Photo-Chemically Induced Dynamic Nuclear Polarization (photo-CIDNP) measurements for the characterization of photo-induced electron transfer processes with metal complexes.

Projetcs

Development and application of CIDNP experiments for the study of the photoreactions of organometallic compounds.

Photo-reactions of organometallic compounds are studied by NMR by illuminating the sample with a laser directly within the superconducting magnet of the spectrometer. The photo-reactions of certain Ru(II) complexes with biological targets (guanosine 5'-monophosphate, tyrosine, tryptophan) give rise to Chemically Induced Dynamic Nuclear Polarization: CIDNP. The (photo)-CIDNP originates from the hyperfine coupling within a pair of (photo-)chemically generated radicals which leads to a modification of the population distribution of nuclear spin states. In the NMR spectrum, reaction products are observed with signals whose intensity can be increased or decreased significantly compared to that observed at equilibrium (without illumination). Stationary CIDNP measures make possible, in particular, to identify the sites of photo-reaction and to characterize the radicals formed with the atomic resolution of NMR. They open up new perspectives for studying the photochemistry of Ru(II) or other transition metal complexes and for the characterization of biological (macro)molecules. The work is carried out in collaboration with the teams of C. Moucheron - A. Kirsch and N. Vaeck.

Characterization of new copper complexes and study of their photoreactions (PhotoCop project)

Homogeneous photocatalysis has been largely dominated by complexes based on noble metals, which have strong limitations, particularly in terms of availability, price and applications. Efficient and robust copper-based photocatalysts are yet to be discovered and this is the heart of the project. New copper complexes (first main objective of the project) and photocatalytic processes using these complexes (second main objective of the project) are developed following a global, integrated and systematic approach, involving catalysis, inorganic/organic chemistry, photochemistry, photophysical and mechanistic studies, and with particular attention to their generality and applicability.
1H, 13C, 31P … NMR measurements in 1 or 2 dimensions are used to characterize synthetic products, including new ligands and the corresponding copper complexes. Very specific NMR measurement protocols, with laser illumination of the sample within the superconducting magnet of the spectrometer via an optical fiber, must be developed and validated to study the photoreactions of the complexes, identify the reaction intermediates and thus elucidate the catalytic cycle(s). The radical intermediates will be characterized by Electronic Paramagnetic Resonance (EPR) measurements, also under laser illumination.