Novel Cationic 2-Phenylpyridine-based Iridium(III) Complexes Bearing an Ancillary Phosphine Ligand: Synthesis, Photophysics and Crystal Structure

摘要

Three novel phosphorescent 2-phenylpyridine-based iridium(III) complexes, [(ppy)2Ir(P^N)]PF₆ (1), [(dfppy)₂Ir(P^N)] PF₆ (2), and [(dfmppy)₂ Ir(P^N)]PF₆ (3), where P^N = 2-[(diphenylphosphino)methyl]pyridine (dppmp), were synthesized and characterized. The absorption, photoluminescence, cyclic voltammetry and thermal stability of the complexes were investigated. The complexes showed bright blue luminescences at wavelengths of 448 ~ 500 nm at room temperature in CHCl₃ and revealed that the ヰ-acceptor ability of the phosphorous atom in the ancillary dppmp ligand plays an important role in tuning emission color resulting in a blue-shift emission. The single crystal structure of [(dfmppy)₂ Ir(P^N)]PF₆ was determined using X-ray crystallography. The iridium metal center adopts a distorted octahedral structure coordinated to two dfmppy and one dppmp ligand, showing cis C-C and trans N-N chelate dispositions. There is a ヰ-ヰ overlap between ヰ electrons delocalized in the difluorophenyl rings.