Theoretical studies of ground and excited electronic states in a series of heteroleptic iridium complexes using density functional theory

A series of new heteroleptic iridium(III) complexes [Ir(C?N)2(N?N)]PF6 (1-6) (each with two cyclometalating C?N ligands and one neutral N?N ancillary ligand, where C?N = 2-phenylpyridine (ppy), 5-methyl-2-(4-fluoro)phenylpyridine (F-mppy), and N?N = 2,2'-dipyridyl (bpy), 1,10-phenanthroline (phen), 4,4'-diphenyl-2,2'-dipyridy (dphphen) were found to have rich photophysical properties. Theoretical calculations are employed for studying the photophysical and electrochemical properties. All complexes are investigated using density functional theory. Excited singlet and triplet states are examined using time-dependent density functional theory. The low-lying excited-state geometries are optimized at the ab initio configuration interaction singles level. Then, the excited-state properties are investigated in detail, including absorption and emission properties, photoactivation processes. The excited state of complexes is complicated and contains triplet metal-to-ligand charge transfer, triplet ligand-to-ligand charge transfer simultaneously. Importantly, the absorption spectra and emission maxima can be tuned significantly by changing the N?N ligands and C?N ligands. (c) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012