Structure–property relationships in a cobalt(II) sulfonamide complex: crystallographic, Hirshfeld surface, spectroscopic, docking and antibacterial investigations

Abstract

Sulfonamide-based metal complexes remain of interest because metal coordination can modify their electronic structure and biological properties. A cobalt(II) complex, bis[4-aminobenzenesulfonamide]bis(dimethylformamide)diaqua-cobalt(II) nitrate (Co-ABS-DMF), was synthesized and investigated to correlate its structure, intermolecular organization, and antibacterial activity. Single-crystal X-ray diffraction reveals a six-coordinate Co(II) center with a distorted octahedral CoN2O4 geometry formed by sulfonamide nitrogen donors, dimethylformamide oxygen atoms, and coordinated water molecules. FT-IR, Raman, and UV–visible analyses confirm coordination through amino nitrogen and carbonyl oxygen donor sites. Supramolecular stabilization is governed by hydrogen bonding, while Hirshfeld surface and interaction energy framework analyses show that O•••H/H•••O contacts contribute 46.4% of intermolecular interactions. Density functional theory calculations indicate electronic polarization and charge redistribution within the metal–ligand framework, supported by frontier molecular orbitals, Mulliken charges, molecular electrostatic potential mapping, and NBO analysis. Molecular docking demonstrates favorable interactions with selected bacterial protein targets through hydrogen bonding and π-mediated contacts. Antibacterial screening shows selective activity against Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, but no detectable activity against Bacillus subtilis. These structural and electronic features are accompanied by a strain-dependent antibacterial response.