New pyrazole-based Schiff base ligand and its Ni(ii) and Co(iii) complexes as antibacterial and anticancer agents: Synthesis, characterization, and molecular docking studies

Abstract New Schiff base of 5-amino-1,3-diphenyl-1 H -pyrazole with 5-bromo salicylaldehyde and its cobalt and nickel complexes have been synthesized by condensation reaction. The synthesized compounds were characterized by numerous spectral (UV–vis, IR, 1 H and 13 C NMR, LC–MS) studies and docking studies. A square planar geometry for Co( iii ) and Ni( ii ) complexes has been proposed. The infrared spectral results confirm the involvement of azomethine nitrogen and phenolic oxygen in the coordination bond formation. The synthesized compounds were evaluated for in vitro antibacterial activity against Bacillus subtilis , Escherichia coli , Staphylococcus aureus , Klebsiella pneumoniae , and anticancer properties against human breast cancer cell lines. The result showed that the zone of inhibition of C1 complex against S. aureus was 16.9 mm, which was closer to the standard drug. On the other hand, C4 complex exhibited the highest cytotoxicity with the lowest IC 50 values of 73.05 μg·mL −1 against human breast cancer cell lines. In addition, molecular docking studies of ligand and complexes with 3TOT, 5MVR, 6D9T, and 6HZQ receptor proteins were conducted. S. aureus shows three hydrogen bond interactions (ASP281, VAL283, ILE36) with a binding affinity of −9.7 kcal·mol −1 for C1 complex over other complexes.