Synthesis and characterization of green-emitting phosphorescent Ir(III) complexes based on phenyl benzimidazole ligand

Several new Ir(III) complexes with 2-(4-bromophenyl)-1H-benzo[d]imidazole or 2-(4-bromophenyl)- 1-methyl-benzo[d]imidazole ligands as cylcometalated ligand and acetylacetonate or picolinate as the ancillary ligand were synthesized and their structures and photophysical properties were characterized. HOMO and LUMO energy levels and the molecular structures of Ir(III) complexes were scrutinized by DFT calculations. The complexes exhibited green luminescence at the maximum emission peaks at ca 495-522 nm. The methyl group substituent and replacing of acetylacetonate with picolinate complex can enhance the complex thermal stability. HOMO energy levels of the complexes vary from -4.99 to -5.44 eV, the LUMO energy levels are between -1.52 and -1.97 eV.