University of Geneva - Switzerland.

Physical Chemistry of Paramagnetic Species (EPR-Spectroscopy)

Département de Chimie Physique

Research activities:

The activities of our group deal with the study of paramagnetic species: their formation, their identification, the determination of their structure, and their reactivity. Two types of molecules are currently investigated: 1) free radicals or radical ions containing an heteroatom (e.g. phosphorus, arsenic, sulphur, germanium...) 2) metal complexes of organic molecules (copper, palladium, platinum...) The paramagnetic species are generated a) in the solid state (single crystals, powders, frozen solutions) by radiolysis or photolysis. b) in the liquid state (chemical reaction, electrolysis, photolysis). Information about these species is obtained from Electron Paramagnetic Resonance and Electron Nuclear Double Resonance.

The purposes of these investigations are:

1) Knowledge of the structure of unstable reaction intermediates.
2) Determination of magnetic properties of some coordination compounds(spin delocalisation on the ligands).
3) Determination of radical mechanisms.
4) Study of a dynamical phenomena (eg. free rotation) in radicals
5) Identification of radiation damage.
6) Study of antioxidation processes.

Some aspects of this research are:

a) Development of new methods in the analysis of EPR/ENDOR spectra (single crystals, powder spectra)
b) Development of methods for the generation of paramagnetic species. (electrochemistry, photolysis, chemical reagents, radiolysis...) and for their trapping.
c) Synthesis of new compounds (organic synthesis and coordination chemistry).
d) Development and use of the simulation programs within density-matrix formalism
e) Quantum chemistry calculations (study of model molecules for the interpretation of the EPR spectra).