Photophysics and electron transfer reactions of [Ru(LL)(CN)4] complexes

Spectroscopic properties of two series of [Ru(LL)(CN)4]2- complexes, where LL=2,2′-bipyridine, 1,10-phenanthroline and their substituted derivatives have been investigated, and the optical spectra of these complexes were compared. It has been demonstrated that the electron donating and withdrawing substituents induce significant blue and red shifts, respectively, in both absorption and emission spectra. The energy of emission originating from the 3MLCT excited state is found to be dependant on the nature of the diimine ligand, on the substituents, and on the electron acceptor properties of the solvent molecules. The rate of radiative and non-radiative decay to the ground state and the parameters of thermally activated deactivation pathways have been estimated using the luminescence lifetime and quantum yields measured at various temperatures. The quenching of luminescent excited state of some selected complexes have been investigated and analyzed by considering the results of magneto kinetic experiments.