Two copper(II) coordination complexes based on sulfanilamide ligand: Synthesis, structure, thermal analyzes, electrochemical properties and biological activities

Abstract Two mononuclear copper(II) complexes of sulfanilamide; [CuL2(NO3)2(H2O)2] and [CuL2(NO3)2(H2O)] with L = 4-aminobenzensulfonamide; were synthesized and characterized using different physico-chemical studies: IR and UV-vis spectra, single crystal X-ray diffraction (XRD), thermogravimetric analysis and electrochemical investigation. In the crystal structures of both complexes, sulfanilamide is found to exhibit a monodentate behaviour coordinating through the amino nitrogen atom. The Cu(II) ion exhibits a distorted octahedral environment in complex (1), while in compound (2) it presents trigonal bipyramidal geometry. The thermal behavior of (1) and (2) was also discussed using TGA/DTA and DSC curves which showed that both complexes acquire good stability at lower temperature. Thermogravimetric data have been utilized to assess the kinetic and thermodynamic parameters using Coats and Redfern integral equations. Electrochemical behavior of the sulfanilamide ligand and its copper(II) complexes (1) and (2) has been investigated at room temperature using cyclic voltammetry technique in DMSO. The Cu(II)/ Cu(I) redox system was found to be consistent with the quasi-reversible diffusion-controlled process. The antimicrobial activity of synthetized metal complexes against various tested organisms such as Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli and Pseudomonas aeruginosa) in different concentration reveals variable responses depending on the strain and the concentration of the compounds tested.