Synthesis, structure, photophysical and electrochemical properties of series of new fac-triscyclometallated iridium complexes with carbazole or oxadiazole moieties

A series of new fac-triscyclometallated iridium complexes Ir(Ln)3 (n = 1–6) (L1: 2-{4-[5-phenyl-[1,3,4]oxadiazol-2-yl]-phenyl}-pyridine, L2: 2-{4-[5-(4-tert-butyl-phenyl)-[1,3,4] oxadiazol-2-yl]-phenyl}-pyridine, L3: 9-(4-pyridin-2-yl-phenyl)-9H-carbazole, L4: 1-[4-(5-phenyl-[1,3,4]oxadiazol-2-yl)-phenyl]-isoquinoline, L5: 1-{4-[5-(4-tert-butyl-phenyl)-[1,3,4] oxadiazol-2-yl]-phenyl}-isoquinoline, L6: 9-(4-isoquinolin-1-yl-phenyl)-9H-carbazole) based on Ir(ppy)3 (ppy = phenyl-pyridine) and Ir(piq)3 (piq = 1-phenylisoquinoline) were synthesized from Ir(acac)3 and corresponding ligands by a new and effective way using anthracene as a solvent. Single-crystal X-ray diffraction spectra of three complexes were studied and the iridium centers were found to adopt distorted octahedral coordination geometry. UV–Vis, photoluminescence, cyclic voltammetry were employed for studying the photophysical and electrochemical properties. These complexes exhibit intense phosphorescence in toluene solution at room temperature with high quantum efficiencies (0.07–0.58) and submicrosecond lifetimes (0.57–0.87 μs).