Room temperature phosphorescence of a palladium(II) complex sensitized by unsymmetric perylene bisimide

摘要

A novel palladium(II) complex (Phpy)Pd(Pery-q) based on cyclopalladated 2-phenylpyridine coordinated to 5-unsymmetric perylene bisi-mide-8-hydroxyquinoline was synthesized and characterized by ~1H NMR, MS-ESI, elemental analysis and IR spectra. The complex displayed room temperature phosphorescence (RTP) in CH2Cl2 solution with a lifetime of ca. 142 mus, arising from the sensitized intraligand charge transfer (~3ILCT) of the appended 8-hydroxyquinoline and was dependent on the ligand orbital perturbed by the metal. Its long-lived emission is affected by aggregation in poly(N-vinylcarbazole) (PVK) film and solid state. The incorporation of an unsymmetric perylene bisimide unit into the 5-substituted-8-hydroxyquinoline ligand prevented thermally activated processes involving non-emissive metal-centered (MC) levels and sensitized (Phpy)Pd in terms of access to the ~3ILCT state. The singlet state of perylene bisimide assisted by heavy metal results in the existence of intersystem crossing to ~3ILCT of the 8-hydroxyquinoline ligand, thus radiatively decaying to the ground state of (Phpy)Pd(Pery-q).