Phosphorescent Cyclometalated Iridium(III) Complexes Based on Amidate Ancillary Ligands: Their Synthesis and Photophysical Properties

A series of quinolyl-substituted iridium(III) compounds with an amidate ancillary ligand and a four-membered-ring structure have synthesized and characterized by X-ray crystallography for the first time. The strategy of varying the amidate ancillary ligand gives photoluminescence in the green and orange-yellow region, while pyridyl-substituted compounds only gave green emission. The HOMO and LUMO energy levels and compositions of quinolyl-substituted iridium (III) compounds were investigated by DFT calculations. This showed that the quinoline and amidate ancillary ligand influence the absorption and emission energies of these complexes by tuning the HOMO energies. In addition, the TG experiment showed quinolyl-substituted iridium(III) compounds have excellent stability. ECL experiments were also explored in this paper.