Theoretical investigation on the spectroscopic properties of cyclometallated iridium (III) complexes and the deprotonation influence on them in solution

摘要

Electronic structures and spectroscopic properties of mixed-ligand cyclometallated iridium complexes with general formula [Ir(N^C) _2(N^N)]~+ (N^C = 2-phenylpyridine, N^N = Hcmbpy = 4-carboxyl-4′-methyl-2,2′-bipyridine, 1; H_2dcbpy = 4,4′-dicarboxyl-2,2′- bipyridine, 2) were studied theoretically. The geometries of the complexes in ground and excited state were optimized at B3LYP and CIS levels, respectively. The absorption and emission of the complexes in CH_3CN solutions were calculated by time-dependent density functional theory (TD-DFT) with the PCM solvent model. The calculated absorptions and emissions of the complexes are in good agreement with the measured results. The deprotonation influence on the electronic structure and the optical properties of 2 was also investigated. The results indicate that the deprotonation which occurs on the COOH groups influences the geometries of the complexes in ground and excited state slightly but leads to significant blue-shifts in low energy absorption and emission maximum.