Design and syntheses of blue luminescent Cu(II) and Zn(II) polymeric complexes with 2-(2′-pyridyl)benzimidazole derivative ligand

The polymeric complexes of 4,4′-bis[2-(2′-pyridyl)benzimidazolyl]biphenyl (Bmbp) with Cu(II) ( 1), Zn(II) ( 2) and 1,3,5-tris[2-(2′-pyridyl)benzimidazolyl]benzene (Tmb) with Cu(II) ( 3), Zn(II) ( 4) were successfully synthesized and characterized by IR spectroscopy, elemental analysis, thermal analysis and conductivity measurements. The results indicate that the stoichiometry of these metal complexes is metal: Bmbp (or Tmb) = 1:1 for 1 and 2 (2:1 for 3 and 4). Ligands coordinated with metal ions to get a five-membered chelate ring and formed polymeric complexes with metal ion. Their luminescence properties were also studied by UV–vis and fluorescence spectra. At room temperature, complexes 1–4 emit blue luminescence from 419 to 483 nm in the solid state and purple/blue luminescence from 385 to 437 nm in DMF solution. Thermal properties measurement and analysis shows that they have good thermal stabilities.