Cobalt (II) Complexes with Schiff Base Ligands Derived from Terephthalaldehyde and ortho-Substituted Anilines: Synthesis, Characterization and Antibacterial Activity

Abstract

In this study, N-propyl-benzoguanamine-SO3H magnetic nanoparticles (MNPs) were used as a catalyst for the synthesis of new Schiff base ligands from condensation reaction of terephthalaldehyde and ortho-aniline derivatives. The bioactive ligands and their cobalt (II) complexes were characterized with nuclear magnetic resonance (1H-NMR), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Visible), mass spectroscopy studies and molar conductance. The antibacterial activity of ligands and their metal complexes were screened using disc diffusion and broth dilution methods against Escherichia coli, Serratia marcescens, Pseudomonas aeruginosa (gram negative bacteria), Bacillus Subtilis and Staphylococcus aureus (gram positive bacteria). The ligands with hydroxyl group showed better biological activity when compared to other ligands. The results showed that the metal complexes have much higher antibacterial activity compare to the parent ligands. It was found that the CoL3 complex was more effective than other metal complexes used against all types of bacteria tested and it was more effective against Pseudomonas aeruginosa with diameter inhibition zone of 17 mm and minimal inhibitory concentration value of 0.15 mg/mL.

Keywords

• terephthalaldehyde
• ortho-aniline derivatives
• Schiff base ligand
• antibacterial activity
• disc diffusion method
• broth dilution method