Synthesis, characterization, crystal structure and biological studies on nicotinanilide based nickel(II), copper(II) and zinc(II) complexes

Three mononuclear Ni(II), Cu(II) and Zn(II) complexes were prepared by reacting the organic ligand N-phenyl-3-pyridinecarboxamide(NAL) and sodium azide with corresponding metal nitrates in MeOH medium. The isolated metal complexes were characterized by elemental analysis, electronic absorption and infrared spectra. The X-ray crystallographic analysis of the Zn(II) complex revealed a distorted tetrahedral geometry. The electronic spectrum of the Zn(II) complex showed characteristic peaks due to the ligand in the UV region and Cu(II) and Ni(II) complexes showed absorption bands both in UV and visible region. These spectral data suggest a distorted tetrahedral geometry for the metal complexes. Electrochemical studies of all the mononuclear complexes show one-electron irreversible reduction wave in the cathodic region while the nickel(II) complex shows one-electron irreversible oxidation wave in the anodic region. EPR spectra of the mononuclear copper(II) complex shows four lines, characteristic of a distorted tetrahedral geometry. All complexes when screened for antibacterial and antifungal activity, showed good antimicrobial activity.