Synthesis of Schiff base ligands from salicylaldehyde as potential antibacterial agents: DFT and molecular docking studies

Abstract

In this research, a number of Schiff base ligands (1–6) were synthesised from salicylaldehyde, as well as their in vitro antibacterial activities were tested against gram-positive (Streptococcus agalactiae, Staphylococcus aureus) and gram-negative (Escherichia coli, Shigella sonnei) bacterial strains by disc diffusion method. All of the synthesised compounds exhibited excellent antibacterial activity, where the compound-5 showed higher activity than others and maximum activity found against S. agalactiae. In addition, molecular docking studies and quantum chemical calculations by density functional theory (DFT) with B3LYP/6-311++G(2d,p) basis set were performed to elucidate the experimental findings. Both molecular docking studies and quantum chemical calculations reveal that the Schiff base ligands show significant binding affinity and excellent reactivity. These computational studies also confirm that the compound-5 exhibits the highest reactivity and best antibacterial activity.