Efficient charge separation in porphyrin-fullerene-ligand complexes.

Photoprocesses associated with the complexation of a pyridine-functionalized C60 fullerene derivative to ruthenium- and zinc-tetraphenylporphyrins (tpp) have been studied by time-resolved optical and transient EPR spectroscopies. It has been found that upon irradiation in toluene, a highly efficient triplet-triplet energy transfer governs the deactivation of the photoexcited [Ru(tpp)], while electron transfer (ET) from the porphyrin to the fullerene prevails in polar solvents. Complexation of [Zn(tpp)] by the fullerene derivative is reversible and, following excitation of the [Zn(tpp)], gives rise to very efficient charge separation.

Simulation of EPR and time resolved EPR lineshapes in partially ordered glasses.

Simulation of magnetic resonance spectra of probes in partially ordered glasses requires in principle a numerical integration on the full set of three Euler angles omega=(alpha beta gamma) from a laboratory fixed to a molecule fixed reference frame. It is shown that it is possible to manage efficiently this problem by using the algebraic properties of the Wigner matrix elements. This analysis is applied to time resolved EPR (TREPR) spectra of a series of bis-adducts of C60 in the ordered glass of a nematic liquid crystal solvent.