Radiative and nonradiative processes of meridional and facial isomers of heteroleptic iridium-trischelete complexes

Photophysical properties of meridional (mer) and facial (fac) isomers of eight iridium(III) trischelete complexes composed of combination of two ligands, 2-(p-tolyl)pyridine and 2-phenylpyrazole, were investigated. Characteristics of heteroleptic complexes were compared to the homoleptic complexes. Phosphorescence radiation process is rationally explained by inter-ligand energy transfer, however, mer → fac isomerization showed different behavior indicating participation of another excited state.