Color Tuning of Blue Phosphorescence: New Iridium Complexes Containing a Bipyridine Derivative and Various Ancillary Ligands

Abstract

New blue-phosphorescent iridium complexes containing 2,6-difluoro-3-(4-methylpyridin-2-yl)pyridine (4-Me-dfpypy) and various ancillary ligands, acetylacetonate (acac) and 2-(5-tert-butyl-2H-1,2,4-triazol-3-yl)pyridine (trzl-CMe3), were synthesized and their photophysical properties were investigated. The main ligand, 4-Me-dfpypy, was designed for development of the blue light-emitting iridium complexes by introducing the electron-donating group, CH3, at the para positions of the pyridine ring determining the LUMO level. The resulting iridium complexes, Ir(4-Me-dfpypy)(3), Ir(4-Me-dfpypy)(2)(acac) and Ir(4-Me-dfpypy)(2)(trzl-CMe3) exhibited the blue emission at 450, 442 and 435 nm in CH2Cl2 solution, respectively. The trzl-CMe3 ancillary ligand in the heteroleptic complex had a stronger effect on hypsochromic shift in PL of its iridium complex than acac ancillary ligand and even further than homoleptic main ligands.