Synthesis of New Schiff Base Ligand and Its Complexes in The Presence of Some Transition Metal Ion and Evaluation of Their Antibacterial Properties

ABSTRACT         Background and objectives: Synthesis and characterization of several metal complexes (metal ions: Co2+, Ti4+ and Ce3+) of macroacyclic Schiff base ligand have been reported. The Schiff base ligand is prepared from the condensation reaction of 1, 4-di-(4-fluoro-2-aminophenoxy) butane with salicylaldehyde in ethanol. In addition, antibacterial activity of metal ions, Schiff base ligand and their complexes have been investigated. Recent studies show that many Schiff base complexes have antibacterial activity against Gram-positive and Gram-negative bacteria. Therefore, we aimed to synthesize new Schiff base complexes and evaluate their antibacterial activity against a number of Gram-positive and Gram-negative bacteria.          Methods: Schiff base ligand and their complexes were characterized by mass spectrometry and IR, H-NMR and C-NMR spectroscopy. The in vitro antibacterial activity of the Schiff base ligand, metal ions and their complexes were evaluated against some Gram-positive and Gram-negative bacteria by disk diffusion method and determining minimum inhibitory concentration.           Results: In this study, the Schiff base complexes had good antibacterial activity, but the Schiff base ligand and metal ions did not show any antibacterial effect. In some cases, the antibacterial effect of the complexes was higher than that of the standard antibiotics tetracycline and gentamycin. The titanium complex showed the highest antibacterial activity in both methods. This complex created the largest growth inhibition zone (diameter: 100mm) against Staphylococcus aureus, and had the lowest minimum inhibitory concentration against Bacillus subtilis (6.75 mg/ml).           Conclusion: The compounds synthesized in our study have strong antibacterial activity.           Keywords: Schiff base complex, Schiff base ligand, antibacterial activity, Staphylococcus aureus, Bacillus subtilis.