Ligand Effects on Luminescence of New Type Blue Light-Emitting Mono(2-phenylpyridinato)iridium(III) Complexes

Newly prepared hydrido iridium(III) complexes [Ir(ppy)(PPh3)2(H)L]0,+ (ppy = bidentate 2-phenylpyridinato anionic ligand; L = MeCN (1b), CO (1c), CN− (1d); H being trans to the nitrogen of ppy ligand) emit blue light at the emission λmax (452−457, 483−487 nm) significantly shorter than those (468, 495 nm) of the chloro complex Ir(ppy)(PPh3)2(H)(Cl) (1a). Replacing ppy of 1a−d with F2ppy (2,4-difluoro-2-phenylpyridinato anion) and F2Meppy (2,4-difluoro-2-phenyl-m-methylpyridinato anion) brings further blue-shifts down to the emission λmax at 439−441 and 465−467 nm with CIE color coordinates being x = 0.16 and y = 0.18−0.20 to display a deep-blue photoemission. No significant blue shift is observed by replacing PPh3 of 1a with PPh2Me to produce Ir(ppy)(PPh2Me)2(H)(Cl) (1aPPh2Me), which displays emission λmax at 467 and 494 nm. The chloro complexes, [Ir(ppy)(PPh3)2(Cl)(L)]0,+ (L = MeCN (2b), CO (2c), CN− (2d)) having a chlorine ligand trans to the nitrogen of ppy also emit deep-blue light at emission λmax 452−457 and 482−487 nm.