Synthesis, Characterization and Antimicrobial Evaluation of Schiff Base Ligands Derived from Ampicillin and their Metal (II) Complexes

Two Schiff base ligands were generated by the condensation of amoxicillin with furfuraldehyde (HL1) and vanillin (HL2). The Cu(II) and Ni(II) complexes of the Ampicillin-Schiff base ligands were successfully produced under reflux in 1:2 metal-to-ligand molar ratio. Spectroscopic and physicochemical techniques such as elemental analysis, melting point, molar conductivity, UV−Visible, FTIR, 1H NMR, 13C NMR, and mass spectrometry were utilized for the characterization of the synthesized compounds. The antimicrobial activity of the synthesized Schiff base ligands and their metal complexes against different strains of bacteria which include Staphylococcus aureus, Staphylococcus pyogenes, Escherichia coli, Salmonella Typhi and Candida albicans, were tested using disc diffusion method. According to the physical characteristic data, the compounds are stable at room temperature and exhibited various colour with melting/decomposition temperature ranging from 161-185 ºC. The FTIR spectra reveal that the ligands coordinated to the metal ions through v(C=O), and v(C=N). The UV/Visible spectra suggested that the complexes have tetrahedral geometry. The results of microanalysis and mass spectrometry agreed with the proposed structure. The antimicrobial screening of the Schiff base ligands and the complexes revealed that the complexes have better activity as compared to the free ligands.