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.