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

Abstract

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.

Keywords:

• Antimicrobial activity
• Schiff base
• Carbohydrazide
• EPR and Powder XRD

The authors are thankful to the Chairman, Department of Chemistry, Gulbarga University, Gulbarga for providing laboratory facilities. They also thank IISc Bangalore, STIC Kochi and CDRI Lucknow for ¹HNMR, ESR, Mass, FAB-Mass, XRD and elemental data.