Cobalt(III) complex of substituted nalidixic acid: Synthesis, characterization (IR, UV, EPR), single crystal X-ray, antimicrobial activity, Hirshfeld surface analysis and molecular docking

Abstract

The mixed–ligand title complex, [Co(nal)2(py)2].4H2O (Hnal=nalidixic acid, py=pyridine), was synthesized. Its structural properties were characterized by X–ray diffraction technique (XRD) and elemental analysis. The spectroscopic properties are investigated by Fourier transform infrared spectroscopy (FT–IR), UV–Vis spectroscopy and EPR spectroscopy. The Co(II) ion has slightly distorted octahedral geometry surrounded by two oxygen atoms of keto and carboxyl groups bonded as chelate from nalidixate, two nitrogen atoms from two pyridine ligands. The monomer are connected by C–H···O and C–H···C interactions to form sheet structures. The FT-IR studies of the complex were commented, focusing on the shifts in the vibrational peaks between the complex form and free nalidixic acid. The powder EPR spectra of Cu(II)-doped complex were investigated at room and at liquid nitrogen temperature. The EPR and UV–Vis spectroscopy studies showed that the unpaired electrons were found in the dx2−y2 orbitals by calculating the spin-Hamiltonian and bond parameters. 2D and 3D Hirshfeld analyses were performed in order to quantify the order and nature of intermolecular interactions in crystal network. Antibacterial activity of complex was studied against S. aureus, B. subtilis, P. aeruginosa, E. coli, C. albicans and A. flavus by using the micro dilution. The optimized complex is docked to 5J9B (S. aerous), 5BMM (E. Coli), 5HTG (C. Albicans), 1ZUV (B. Subtilis), 4F0V (P. aeruginosa) and 4YNU (A. flavus).