Synthesis, Physicochemical Characterization, and Metal Complexation of Novel Azo-Diketone Sulfonamide Derivatives

This study synthesised two novel azo-diketone ligands (N1 and N2) based on sulfonamides, investigated their complexation with copper(II) and nickel(II) ions, and elucidated the structural properties and coordination patterns of the resulting compounds. We prepared the ligands via a standard diazotisation and coupling protocol, and synthesised the solid metal complexes by direct coordination at a 2:1 molar ratio. We characterised the complex systems using a multi-analytical approach and assessed their biological activity. The results showed the formation of (2:1) complexes with high thermal stability. The copper complexes exhibited a planar square structure, while the nickel complexes had an octahedral structure. Bioassays showed that mineralisation significantly enhanced antioxidant and antimicrobial activity. The N2Cu complex had an IC50 of 16.8 lemda g/mL, close to ascorbic acid. Copper complexes also exhibited low minimum inhibitory concentration (MIC) values, as low as 0.5 mg/mL, against S. aureus. The N2Cu complex surpassed this, with an inhibition zone diameter of 28 mm, demonstrating high efficacy against bacteria and fungi. The results confirm the potential use of copper-sulfonamide complexes as therapeutic agents and highlight the crucial role of metal ion selection in metal drug design.