New blue phosphorescent iridium complexes containing phenylpyridine and triazole ligands: synthesis and luminescence studies.

The synthesis and luminescence of iridium(III) complexes containing new phenylpyridine (C(see test for symbol)N) ligands, 4-Me-4'-F-ppy, 4-Me-4'-CF3-ppy and 4-OMe-4'-CF3-ppy, were studied. These ligands were designed for development of the blue light-emitting iridium complexes by introducing the electron-withdrawing group (F, CF3) and the electron-donating group (Me, OMe) at the para positions of the phenyl and pyridine ligand rings, respectively. As an ancillary ligand, trzl-CMe3 was employed where trzl-CMe3 represents 2-(5-tert-butyl-2H-1,2,4-triazol-3-yl)pyridine. The resulting iridium complexes, Ir(4-Me-4'-F-ppy)2(trzl-CMe3), Ir(4-OMe-4'-CF3-ppy)2 (trzl-CMe3) and Ir(4-Me-4'-CF3-ppy)2(trzl-CMe3) exhibited the blue emission at 472, 484 and 494 nm in CH2Cl2 solution, respectively. Ir(4-Me-4'-F-ppy)2(trzl-CMe3) showed the most hypsochromic shift in photoluminescence (PL) among the complexes prepared herein. In the electroluminescence (EL) spectra, Ir(4-Me-4'-F-ppy)2(trzl-CMe3) and Ir(4-Me-4'-CF3-ppy)2(trzI-CMe3) exhibited the luminescence peak at 437 nm and 496 nm, respectively. In the aspect of blue emission color purity, Ir(4-Me-4'-F-ppy)2(trzl-CMe3) had the CIE coordinates of (0.176, 0.143), very close to the saturated standard blue emission.