Synthesis and luminescent properties of polymeric metal complexes containing bis(8-hydroxyquinoline) group

A novel ligand: 4,4′-bis(8-hydroxyquinoline-5-propenyl)-biphenyl (B8QPB) (1), has been synthesized by Witting-Horner reaction, and the corresponding two polymeric metal complexes were also prepared by polynuclear of the ligand with aluminium (III) (2) and zinc (II) (3) halides, respectively. The structure of the ligand was characterized by ¹H NMR, FT-IR and elemental analysis techniques; polymeric metal complexes were characterized by FT-IR, UV-vis, elemental analysis techniques, conductivity measurements and gel permeation chromatography (GPC). The results indicate that the stoichiometry of polymeric metal complexes is [(C₃₄H₂₄O₂N₂)₁₁Al₁₂Cl₂₈] and [(C₃₄H₂₄O₂N₂)₃₂(ZnCl₂)₃₃]. B8QPB coordinated with metal ions to form polymers. The luminescence properties of the complexes 1-3 were investigated by UV-vis and fluorescence spectra at room temperature. The experimental results show that polymeric metal complexes 2 and 3 emit blue/green luminescence at 514 and 504 nm in the solid state and at 470 and 507 nm in DMSO solution. Thermal properties measurement and analysis show that they have good thermal stabilities.