Synthesis, Characterization, Antibacterial and Antioxidant Activities of Cu(II), Ni(II), and Zn(II) Mixed Ligand Complexes Containing Isoniazid Based Bidentate Schiff Base

Two mixed ligands (L1, L2), L1 = N-(4-methoxybenzylidene) isonicotinohydrazone, L2 = 2-aminophenol, and their metal (Cu2+, Ni2+, and Zn2+) complexes with stoichiometry (1:1:1) were synthesized and characterized by analytical and physico-chemical techniques such as conductivity, magnetic susceptibility measurements, IR-spectra, and UV-Visible spectra. All of the metal complexes were 1:1 electrolyte, according to the molar conductance measurements. It can be concluded from the IR study that the ligands were coordinated to the corresponding metal ions through N and O donor sites of the azomethine nitrogen atom and the carbonyl oxygen atom. Magnetic moment and UV-Vis spectra data confirmed that square planar geometry for Cu(II) and Ni(II) complexes, and tetrahedral structure for Zn(II) ion complex. The metal complexes derived from L1 and L2 were tested against Escherichia coli and Pseudomonas sp. Among the tested compounds, Cu(II) complex showed higher antibacterial activity over both bacterial strains against reference drug Kanamycin-30. Moreover, synthesized metal complexes exhibited moderate antioxidant activity than the Schiff base. Cu(II) complex was found to be most active whereas, Zn(II) complex showed the lowest antioxidant activity comparable to the BHT.