Studies on the mixed ligand complexes of copper(II) involving a sulfa drug and some potentially bi or tridentate ligands under physiological conditions

The stability constants of mixed ligand complexes formed in the Cu(II)-sulfathiazole(stz)(A)-glycine(gly), dl-2-aminobutanoic acid(2aba), dl-3-aminobutanoic acid(3aba), 1,2-diaminopropane(dp), 1,3-diaminopropane(tp), dl-2,3-diaminopropanoic acid(dapa), dl-2,4-diaminobutanoic acid(daba), dl-2,5-diaminopentanoic acid(ornithine, orn)(B) systems have been determined pH-metrically at 37 °C and I = 0.15 mol dm−3 (NaClO4) using SCOGS program. Analysis of experimental data indicates the presence of CuABH, CuAB, CuAB2H2 or CuAB2 species. The Δlog K values demonstrate higher stabilities for the mixed ligand complexes compared to the binary analogues. The CuAB complexes with B = gly, 2aba, dapa & orn systems were isolated and characterized using micro analytical, magnetic moment, ESR, electrochemical studies, TG/DTA, power XRD and SEM analysis. Magnetic susceptibility and electronic spectral studies suggest square planar geometry for the CuAB complexes. The g   values indicate that the unpaired electron lies in the dx2-y2dx2-y2 orbital. The TG/DTA studies reveal that the complexes are non hydrated and possesses high thermal stability. The powder XRD data suggest that the complex is microcrystalline. The antimicrobial activity and CT DNA cleavage studies of the complexes are also reported.