Synthesis, crystallography, phosphorescence of platinum complexes coordinated with 2-phenylpyridine and a series of β-diketones

Metallocyclic platinum(II) complexes coordinating with 2-phenylpyridine (ppy) and a series of β-diketone ancillary O∧O ligands, (ppy)Pt(acac), (ppy)Pt(ba), (ppy)Pt(dbm), and (ppy)Pt(tta) (acac = acetylacetone, ba = benzoylacetone, dbm = dibenzoylmethane, tta = thenoyltrifluoroacetone) were synthesized. The crystal structure, absorption, emission, quantum yield and phosphorescence life time were characterized. As the conjugative π system of the O∧O ligand increases in the order acac < ba < dbm, or there is a group –CF3to attract the electron density of the tta ligand, the quantum yield decreases in the order (ppy)Pt(acac) > (ppy)Pt(ba) > (ppy)Pt(dbm) > (ppy)Pt(tta) due to an energy back-flow from ppy to the O∧O ligand, a trend also in contrast to the phosphorescence emission spectra and time decay (biexponentially, ∼0.7–13 μs).