Synthesis and Comparative Antibacterial Studies on Ni (II) and Cu (II) Complexes from some Amino Acid Derivatives

Abstract

Schiff base ligands Ethane-1,2-diylbis-2-aminoacetimidic acid (L1) and Ethane-1,2-diylbis-2- aminopropanimidic acid (L2), along with their corresponding metal (II) complexes of Ni and Cu, were synthesized and characterized through Fourier Transform Infrared (FT-IR) and UV-Visible spectral analysis, melting point/decomposition temperature measurements, solubility assessments, molar conductivity evaluations, and magnetic susceptibility test. The sharp melting points of the ligands and decomposition temperatures of the complexes indicate their purity. The compounds were predominantly insoluble in non-polar organic solvents but soluble in polar solvents, presuming their polar characteristics. The conductivity measurements demonstrate the electrolytic properties of the compounds, correlating with their solubility in polar solvents. Magnetic susceptibility results indicate that the complexes are paramagnetic, exhibiting tetrahedral geometries in all the Ni (II) complexes and distorted octahedral structures in Cu (II) complexes. The antibacterial activities of the compounds were evaluated against gram-positive Staphylococcus aureus and Streptococcus pneumoniae, as well as gram-negative Escherichia coli and Pseudomonas aeruginosa isolates, the results generally revealed higher activity in L1 complexes compared with L2 complexes.