Antimicrobial Activities of Co(II),Ni(II),Cu(II) and Zn(II) Metal Complexes Derived from Tetradentate Schiff Base Ligands

Abstract

New Schiff base Co(II),Ni(II),Cu(II) and Zn(II)  metal complexes have been synthesized from the tetradentate Schiff base ligands, L₁ and L₂ synthesized by the condensation of 4-aminoacetophenone, p-phenylenediamine and salicylaldehyde or 5-chlorosalicylaldehyde. [L₁ = C₃₆H₃₀N₄O₂ and L₂= C₃₆H₂₈N₄O₂Cl]. The complexes have been characterized by elemental analysis, IR, ¹H NMR, UV-Vis spectra, electrochemical, molar conductance, ESR and magnetic moment studies. Elemental analysis data and molar conductance measurements revealed that the complexes are electrolytic in nature. IR spectra of the complexes show that the ligand coordinates to the metal ion through the four azomethine nitrogen atoms and the two phenolic oxygens were free from coordination. Based on the magnetic moment and electronic spectral data a square planar geometry has been approximately suggested for all the complexes. The redox behavior of the complexes was explained by cyclic voltammetry. The Schiff base metal complexes are found to have the general formula [M L₁ orL₂](OAc₂), where M = Co, Ni, Cu and Zn. Antibacterial and antifungal screening of the ligands and its metal complexes reveal that all the complexes show higher activities than the ligands. The antimicrobial studies also reveals that the complexes derived from the ligand L₂ were found to be more potent than the complexes derived from the ligand L₁.