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 λ_max (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 λ_max 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 λ_max 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 λ_max 452−457 and 482−487 nm.