Phosphorescent C∧C* Cyclometalated Thiazol-2-ylidene Iridium(III) Complexes: Synthesis, Structure, and Photophysics

The synthesis and characterization of the first cyclometalated arylthiazole-based iridium­(III) phosphorescent emitters of the general structure IrL2(acac) with L = 3-(4-bromophenyl)-4,5-dimethyl-1,3-thiazol-2-ylidene and 3-(4-methylphenyl)-4,5-dimethyl-1,3-thiazol-2-ylidene and acac = acetylacetonato is presented. All complexes were isolated isomerically pure and were unambiguously assigned by a solid-state structure, DFT calculations, and 2D NMR studies. Investigation of their emission behavior revealed emission maxima at 495 ± 5 nm. Quantum chemical calculations were used to calculate the energy differences between the possible isomers and to understand the emission behavior.