Synthesis, characterization, antioxidant and antimicrobial activities of a heptadentate N4O3-type Schiff base ligand and its metal complexes

Mo(III), Fe(III), Cd(II), Zn(II), Cu(II) complexes based on Tris[2-salicylaldeneimino)ethyl]amine (H3saltren) have been successfully synthesized. Newly prepared compounds have been characterized by 1H-NMR, 13C-NMR, IR and UV–VIS spectroscopy techniques. The spectral studies confirmed the ligand coordinates the metal ion to form complex via the oxygen and nitrogen atoms of the phenolic group and azomethine group. The antioxidant activity of the ligand and its complexes were determined by DPPH (2,2-diphenyl-1-picryl-hydrazyl) method in vitro. The obtained IC50 value of the DPPH activity for the copper complex (IC50 = 55.30 mg/ml) was higher than other compounds. Furthermore, the antimicrobial effects of the tested compounds have been tested against the bacterial species, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus by Disc diffusion and Micro-broth dilution methods. It has been found that the Cu complex has more effective against Bacillus cereus and the Cd complex showed the best antibacterial activity against the Staphylococcus aureus.