A rare case of dual emission in a neutral heteroleptic iridium(III) complex

Herein we describe the synthesis and characterization of a neutral heteroleptic iridium complex bearing an unusual 2-pyridyl-6-methylthiazine dioxide ligand (pythdo). X-ray crystallographic analysis reveals that in the complex, the pythdo ligand is twisted and puckered, resulting in very low photoluminescent quantum efficiency. The emission profile is structured. Excited state lifetime measurements along with oxygen quenching studies point to a rare case of dual emission from different excited states whereby the high energy bands possess significant ligand-centered (3LC) character while the lower energy bands are predominantly characterized as a mixture of charge transfer (3CT) states. A detailed computational analysis corroborates the unusual photophysical behavior.