Luminescent metal complexes. Part 2. A model for the luminescence properties of the tris-chelates of substituted 2,2′-bipyridyls with ruthenium (II)

Abstract

A three-state model is presented to explain the variations in the quantum efficiencies within a series of complexes formed from 26 2,2′-bipyridyl ligands with ruthenium(II). The radiative rate constants are shown to vary with the molar absorptivity for the singlet d→π* transitions. Ln k_N(non-radiative rate constant) for complexes bearing +M–I and +M+I groups at the 4– and 4,4′-positions of the ligands vary with the energy gap. A parallel is noted between the metal-to-ligand charge-transfer process and the charge-transfer transition from a metal ion impurity to the conducting band of a semiconducting lattice.