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).

By incorporating hole-transporting carbazole or electron-transporting oxadiazole moieties, six fac-triscylcometallated iridium(III) complexes have been synthesized by a new method with good yield. The Ir(ppy)3 based compounds, Ir(L1)3–Ir(L3)3, show green or yellowish green color centered at ca. 503–540 nm and the Ir(piq)3 based complexes, Ir(L4)3–Ir(L6)3, display red emission located at ca. 611–631 nm due to the MLCT emission. The complexes Ir(L1)3–Ir(L3)3 are potential materials for the application in OLEDs due to the efficient photoluminescence emission and high quantum efficiency Фp.Figure optionsDownload as PowerPoint slideHighlights
► We synthesize six iridium(III) complexes with carbazole or oxadiazole moieties.
► The Ir(ppy)3 based compounds show green or yellowish green color (503–540 nm).
► The Ir(piq)3 based complexes display red emission (611–631 nm).
► The complexes Ir(L1)3–Ir(L3)3 are potential materials for the application in OLEDs.