Thiol stabilized Co-Ni bimetallic nanoclusters for antibacterial activity and computational insights

The water-soluble bimetallic ultrasmall Co–Ni nanoclusters (Co-NiNCs) have been synthesized and characterize in different analytical approaches such as optical, thermal, antibacterial and bioinformatic studies. The as synthesized Co–NiNCs exhibited a pronounced absorption band at 341 nm in the UV–Vis spectrum, attributed to metal-to-ligand charge transfer and interband d–d electronic transitions, thereby consistent with quantum confinement effects and formation of ultrasmall bimetallic nanoclusters. Furthermore, Tauc plot analysis revealed dual optical band gaps of 2.88 and 3.88 eV, signifying tunable semiconducting characteristics with multiple electronic transition pathways induced by nanoscale confinement and synergistic Co–Ni electronic interactions. The TGA analysis confirms high thermal stability, presenting an ∼80% weight loss due to the decomposition of organic ligands and stabilization above 450 °C. Antibacterial assays using E. coli showed a clear dose dependent growth inhibition comparable to a standard antibiotic. The molecular docking studies where there are favorable interactions of the ligand-modified nanoclusters and active sites of bacterial protein stabilized by hydrogen bonding, π-π stacking and van der Waals interactions. Based on the collective properties and the docking score is −7.8 kcal/mol, thiol-stabilized Co-NiNCs suggest potential applicability for both optoelectronic and potential biomedical applications.