Synthesis and Crystal Structure of Blue Phosphorescent mer-Tris(2',6'-difluoro-2,3'-bipyridinato-N,C^4') Iridium(III)

Abstract

A blue phosphorescent <TEX>$Ir(dfpypy)_3$</TEX> (dfpypy:fluorinated pyridine-pyridine ligand) complex with meridional configuration has been synthesized by newly developed effective method and its solid state structure and photoluminescence are characterized. For this complex, mer-<TEX>$Ir(dfpypy)_3$</TEX>, the glass-transition and decomposition temperatures appear at <TEX>$160^{\circ}C$</TEX> and <TEX>$384^{\circ}C$</TEX> respectively in TGA and DSC experiments, which indicates that this complex has high thermal stability. In a crystalline structure, an average Ir-C bond length of mer-<TEX>$Ir(dfpypy)_3$</TEX> is slightly longer than that of fac-<TEX>$Ir(dfpypy)_3$</TEX>, which assumed to be due to the weak trans-influence. The absorption and emission spectra are observed more red-shifted in mer-<TEX>$Ir(dfpypy)_3$</TEX> than fac-<TEX>$Ir(dfpypy)_3$</TEX>. In addition, the former is readily oxidized than the latter in electrochemical behavior.