Tuning the color and phosphorescent properties of iridium(III) complexes with phosphine-silanolate ancillary ligand: A theoretical investigation

Abstract

A series of Ir(III) complexes [(CˆN)2Ir(PˆSiO)], where (CˆN)H is 2-phenylisoquinoline (1), 2-phenylpyridine (2) or 2-(2,4-difluorophenyl)pyridine (3), and (PˆSiO)H is an organosilanolate ancillary chelate with either diphenylsilyl (a) or dimethylsilyl (b) substituent, are investigated by means of the density functional theory/time-dependent density functional theory (DFT/TD-DFT). Their relationship between structure and property is evaluated by the geometries, electronic structure, and absorption and phosphorescence spectra associated with the internal quantum yield. The effect of different substitutions on the ancillary ligand is explored by compare of the complexes 1a (2a/3a) and 1b (2b/3b). Furthermore, five complexes, 2b-1, 2b-2, 2b-3, 2b-4, and 2b-5, are newly designed by introduction of the substitution groups on the phenyl rings of the 2b (See Fig. 1). The theoretical result estimates that the complexes 2b-1, 2b-2, 2b-4, and 2b-5 would be the blue-emitting phosphors. Especially, the complex 2b-1 has a higher quantum yield relative to 2b by comparison of the factors governing the radiative decay rate constants of the emissive state and the feasibility of the deactivation process from the T1 state via triplet metal-centered (3MC) state.