Synthesis, crystal structure, properties, and nuclease activity of a new Cu(II) complex [Cu(L)2(Py)2(H2O)] (HL = N-(5-(4-methylphenyl)-[1,3,4]-thiadiazole-2-yl)toluenesulfonamide)

A new N-sulfonamide ligand, N-(5-(4-methylphenyl)-[1,3,4]-thiadiazole-2-yl)toluenesulfonamide (HL) and its Cu(II) complex [Cu(L)(2)(Py)(2)(H2O)] (I), have been synthesized. The X-ray crystal structure of the ligand and of complex I have been determined (CIF files CCDC nos. 975153 (HL), 851790 (I)). In I, the Cu2+ ion is five-coordinated, forming a CuN4O chromophore. The ligand acts as monodentate, coordinating the metal ion through a single N-thiadiazole atom. The molecules from the reaction medium (pyridine and water) are also involved in the coordination of the Cu2+ ion. Complex I has a slightly distorted square pyramidal geometry. The complex was characterized by FT-IR, electronic, EPR spectroscopic and magnetic methods. The nuclease activity studies of the synthesized complex confirm his capacity to cleavage the DNA molecule. The ligand has two important roles in the nuclease activity of I: it influence the reactivity of the Cu2+ ion and interact with DNA molecule. The complex interacts with the DNA molecule. Immediately, the Cu2+ ion is reduced to Cu(I), and in the presence of molecular oxygen the formed Cu(I) complex produces reactive oxygen species in close proximity to the double helix.