Manipulating Excited State Properties of Iridium Phenylpyridine Complexes with "Push-Pull" Substituents.

We have prepared a series of complexes of the type [Ir(ppy)(L] complexes (), where ppy is a substituted 2-phenylpyridine and L is a chelating phosphine thioether ligand. The parent complex () comprises an unsubstituted phenylpyridine ligand, whereas complex contains a nitro substituent on the pyridine ring, complex features a diphenylamine group on the phenyl ring, and has both nitro and diphenylamine groups. Crystallographic, H NMR, and elemental analysis data are consistent with each of the chemical formulae. DFT (density functional theory) computational results show a complicated electronic structure with contributions from Ir, ppy, and the PS ligand. Ultrafast pump-probe data show strong contributions from the phenylpyridine moieties as well as strong panchromatic excited state absorption transitions. The data show that nitro and/or diphenylamine substituents dominate the spectroscopy of this series of compounds.