Synthesis, Characterization, Electrochemical Studies and Biological Activities of Complexes of Tridentate Schiff Base Ligand with Divalent Metal Ions

A series of novel Schiff base 1-((2-hydroxyphenyl)iminomethyl)naphthalene-2-ol (H2L) and its Cu(II), Co(II), Ni(II), Mn(II),Cd(II) and UO2(II) complexes were synthesized and characterized. The nature of bonding and the geometry of the complexes were deduced from elemental analysis, spectral (FT-IR, UV-Vis., 1H NMR, mass and ESR), magnetic moment, thermal analyses, X-ray diffraction and conductivity measurements. The microbial activity of the compounds was studied using disc diffusion method against bacteria, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and Bacillus subtilis and against fungi, Aspergillus niger, Fusarium oxysporum, Alternaria alternata and Candida albicans. The results indicated that the Ni(II) complex showed the potent antibacterial activities against Staphylococcus aureus and Klebsiella pneumoniae only at 150 µg/mL. The data showed that the antifungal effect of ligand against A. niger was similar to the effect of Co(II), Mn(II), Cd(II) and UO2(II) complexes where the inhibition zone ranged from 23-26 mm at 150 µg/mL concentration .The ligand showed higher interaction value of receptor of Staphylococcus aureus (3q8u) than receptor of Escherichia coli (3t88).The inhibition process of the prepared ligand (H2L) against the corrosion of Concrete Steel Reinforcement in HCl (2 M) solution was determined by various electrochemical methods are found to be in reasonable agreement.