Color tunable phosphorescent iridium complexes with substituted 2-phenylthiazoles as the cyclometalated ligands

Several new iridium complexes with substituted 2-phenylthiazoles as the cyclometalated ligands have been synthesized and characterized to try to investigate the effect of the size of the π system and substituent groups on physical properties. The complexes have the general structure of (C∧N)2Ir(acac), where the C∧N are 2-phenylthiazole (ptz), 2-(4-methylphenyl)thiazole (mptz), 2-(4-ethylphenyl)thiazole (eptz). The absorption, emission, cyclic voltammetry and thermostability of the complexes were systematically investigated. The experimental results revealed that the maximum emission wavelength in CH2Cl2 at room temperature are in the range 542–547 nm, which is blue shift than that of the known iridium(III) bis(2-phenylbenzothiazolato-N,C2′) acetyl acetonate (bt)2Ir(acac) due to decreasing the size of the π system in the benzothiazole portion of 2-phenylbenzothiazole ligand.