Eco-friendly and efficient synthesis, characterisation and antibacterial studies of unsymmetrical bidentate schiff bases and their zn(ii) complexes

Abstract

A rapid, efficient, clean and environmentally benign exclusive synthesis of Schiff bases as new ligands and their complexes with Zn(II) have been developed using condensation of pyridoxal with amoxicillin (L1), cephalexin (L2), sulphamethoxazole (L3) and trimethoprim (L4) efficiently in analcoholic suspension medium using alkali catalyst with excellent yields under microwaves irradiation. This method provides several advantages such as environmental friend liness, simple work-up procedure, short reaction times, non-hazardous and excellent yield of products.The results are compared with conventional methods for their yield and reaction time. The Schiff base ligands and the complexes were characterized by micro-analytical, thermo-gravimetric, magnetic and spectroscopic studies.All the Schiff bases were bidentate (NO donor) ligands. All complexes were found to be six co-ordinate dihydrates and ML2[1:2 (metal: ligand) ratio] type. The complexes are coloured and stable in air. All the complexes under investigation possess antibacterial activity. The antibacterial activity showed the following trend: Zn(II)-complexes > Schiff base ligands > Parent drugs.