Electron-withdrawing groups and strong-field ligands containing iridium(III) complexes and their efficient blue light-emitting

Two new heteroleptic iridium(III) complexes [Ir(4,6-dfppy) ₂(PPh₃)L] (4,6-dfppy = 2-(4,6-difluorophenyl)pyridyl, PPh₃ = triphenylphosphine, L = NCS^-, 1; NCO^-, 2) have been synthesized and fully characterized. By introduction of electron-withdrawing groups such as fluorine atoms on the 4- and 6-positions of 2-phenylpyridyl (ppy) and using strong-field ligands for instance PPh ₃ and pseudohalogen as ancillary ligands, the HOMO-LUMO electronic energy gaps of 1 and 2 have been increased sufficiently. The photoluminescence (PL) spectra of 1 and 2 in solution show emission maxima at 456 and 458 nm, respectively, corresponding to efficient blue light-emitting. X-ray analyses show that intra- and intermolecular π-π interactions exist in the solid state of 1 and 2. The PL spectra of 1 and 2 in solid state exhibit about 30 nm spectral red shifts compared with those in solution.