Syntheses, Characterization And Crystal Structure Of A Novel Polypyridine Ligand And Its Transition Metal Complexes

The coordination compounds, synthesized with transition metal and polypyridines as raw materials, are more and more important as their various structures and extensive uses. The use foreground of these compounds will be extensive in the field of molecular discernment, molecular catalysis, self-assemble, anti-tumour medicine and nucleic acid probe etc. A novel polydentate ligand L, 4,4 -bis[2-(pyridn-2-yl)-imidazol[l,5-a]pyridine made of two bidentate pyridylimidazol halves, separated respectively, has been synthesized and coordinated with metal cation Cu2+, Ni2+ ,Mn 2+and Zn2+ respectively. And the complexes obtained have been characterized by elemental analysis, UV/Vis, fluorescent spectra, ~1H NMR, mass spectrometry. The crystal and molecular structure of L and the complexes [Cu2(L)3] (C1O4)4, [Zn2(L)3] (C1O4)4, [Ni2(L)3] (C1O4)4 have also been determined by X-ray diffraction. The crystal of L is monoclinic with space group P2/c. The ligand consists of the pyridine rings and the imidazol[l,5-a]pyridine rings which are nearly coplanar, indicating that a considerably delocalized π-conjugated system has a great influence on its fluorescent property. As expected, the formation of a dinuclear structure [M2(L)3]4+, (M=Cu2+ Zn2+, Ni2+, Mn2+) with a compact triple helical motif, a compact unit, is confirmed. The transitional metal ions are six-coordinated with three pyridine nitrogen atoms and three imidozle nitrogen atoms from three Hgands L respectively.