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

Three novel phosphorescent 2-phenylpyridine-based iridium(III) complexes, [(ppy)Ir(P boolean AND N)]PF6(1), [(dfppy)2Ir(P boolean AND N)] PF6(2), and [(dfmppy)(2) Ir(P boolean AND N)PF6 (3), where P boolean AND 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 similar to 500 nm at room temperature in CHCl3 and revealed that the pi-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 boolean AND N)]PF6 was determined using X-ray crystallography. The indium 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 pi-pi overlap between pi electrons delocalized in the difluorophenyl rings.