Novel Cd(II) complex bearing naproxen and imidazole ligands: Synthesis, single-crystal X-ray, structural elucidation, quantum chemical investigation, molecular docking, antioxidant and antimicrobial screening

A novel mixed ligand Cd(II) complex [Cd(nap)₂(imd)₃] bearing naproxen and imidazole ligands have been synthesized. Characterization of the mono-nuclear complex was carried out via: ¹H & ¹³C NMR, FTIR, UV–vis and MS and the structure validated with SC-XRD studies. The complex forms a monoclinic crystal structure with space group P₂₁ and a = 13.581(8) Å, b = 8.290(5) Å, c = 16.693(10) Å, a = γ = 90°, b = 109.352(18)°,V = 1773.1(18) ų. FTIR data confirmed the binding of the naproxenato ligand via the deprotonated oxygen atom to the cadmium (II) ion. The coordination sphere around the Cd(II) center is a 7-coordinate system with a distorted pentagonal bipyramidal geometry having a CdN₃O₄ chromophore with bidentate ligation of the carboxylate ligand naproxen. Docking with the ADP-ribosyl transferase binding component protein (PDB: 6v1s) gave a binding affinity of −9.8 kcal/mol for the complex [Cd(nap)₂(imd)₃], establishing eight hydrogen bonds, with the shortest bond length observed in serine. It exhibited greater binding affinity (−9.5 kcal/mol) and established a higher number of hydrogen bonds compared to azithromycin. Tyrosine A:100 exhibited the shortest bond length among the six hydrogen bond interactions detected during docking with prostaglandin reductase 2 (PDB: 2zb7), resulting in a binding affinity of −8.6 kcal/mol. In comparison, ibuprofen demonstrated lower binding affinity (−7.6 kcal/mol) and formed fewer hydrogen bonds. Overall, molecular docking results strongly suggest that [Cd(nap)₂(imd)₃] exhibits high binding affinities with both ADP-ribosyltransferase binding component and prostaglandin reductase 2, indicating its potential as a candidate for treating bacterial infections and inflammation. The complex exhibited higher radical scavenging activity than the unbound ligands but was less than the ascorbic acid standard in the in-vitro antioxidant experiment. The complex showed promising inhibitory action against some bacterial and fungal strains. The current results may be due to the combined impact of the ligands and the metal ion during complex formation.