Synthesis, spectral characterization and biological activity studies of transition metal complexes of Schiff base ligand containing indole moiety

A new series of transition metal complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II), with a tridentate (oxygen nitrogen nitrogen) ligand 3,5-dimethyl-N′-[(1E)-1′-pyridin-2′-ylethylidene]-1H-indole-2-carbohydrazide (L) have been synthesized and characterized on the basis of analytical, magnetic susceptibility, infra red, nuclear magnetic resonance, fast atom bombardment-mass, electron paramagnetic resonance spectral studies, X-ray powder diffraction and UV-visible spectral data. Based on analytical and molar conductance data, the complexes may be formulated as [M(L)2]·(H2O)n, where M˭ Co, Cu and Ni and [M(L)Cl2].(H2O)n, where M=Zn, Cd and Hg. The spectral studies revealed that, an octahedral geometry for Co(II), Ni(II) and Cu(II) complexes, whereas square pyramidal geometry for Zn(II), Cd(II) and Hg(II) complexes. The ligand and its Co(II) complex have been characterized by X-ray powder diffraction studies. The ligand and its complexes were tested for their antibacterial activity against Escherichia coli & Staphyloccocus aureus and antifungal activity against Aspergillus niger & Candida albicans.