Syntheses, crystal structure and luminescent properties of cadmium complexes based on 2,6-bis(1-phenylbenzimidazol-2-yl)pyridine

Two cadmium complexes, Cd(bpbp)Cl2 (complex 1) and [Cd(bpbp)2](ClO4)2 (complex 2), based on 2,6-bis(1-phenylbenzimidazol-2-yl)pyridine (bpbp), were synthesized and characterized by X-ray single crystal structure analyses. For complex 1: crystal system, monoclinic, space group, C2/c, a = 27.427(3) Å, b = 13.4495(15) Å, c = 14.8381(17) Å, β = 106.635(2)°, V = 5244.4(10) Å3, Z = 8. It is a neutral complex. The Cd(II) ion distorted trigonal bipyramidal geometry is five-coordinated by three nitrogen atoms from ligand (bpbp) and two chlorine ions. For complex 2: crystal system, triclinic, space group, P-1, a = 13.4791(15) Å, b = 13.8506(16) Å, c = 16.5839(19) Å, α = 94.202(2)°, β = 106.948(2)°, γ = 94.872(2)°, V = 2935.3(6) Å3, Z = 2. It is an ionic complex. The Cd(II) ion octahedral geometry is six-coordinated by six nitrogen atoms from two ligand (bpbp). Both complexes emit blue luminescence with emission peaks at 420 and 430 nm in solid state and with emission peaks at 415 and 425 nm in DMF solution. In complex 1 absorption spectra, there is not only the free ligand absorption peak at 310 nm, but also shows strong Cd–Cl charge transfer peak at 350 nm in DMF solution.

Graphical abstractTwo cadmium complexes based on 2,6-bis(1-phenylbenzimidazol-2-yl)pyridine (bpbp), were synthesized and characterized by X-ray single crystal structure analyses. Both complexes emit blue luminescence in solid state and in solution.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Two new cadmium complexes based on 2,6-bis(1-phenylbenzimidazol-2-yl)pyridine were synthesized. ► The two cadmium complexes were characterized by single X-ray analyses. ► The two cadmium complexes emit blue luminescence in solid state and in solution. ► The luminescence of the two cadmium complexes are predominantly from the ligand π∗ → π transitions fluorescence.