COPPER(II) COMPLEXES WITH NEW N-SUBSTITUTED SULFONAMIDES – SYNTHESIS, CRYSTAL STRUCTURE AND EVALUATION OF THE NUCLEASE ACTIVITY

Abstract

Binary Cu(II) complexes of two new N-substituted sulfonamides, N-(pyridin-2-yl-methyl)biphenyl-4-sulfonamide (HL1) and N-bis-(pyridin-2-yl-methyl)biphenyl-4-4’-sulfonamide (H₂L2), have been synthesized and characterized by X-ray diffraction, spectroscopic and electrochemical techniques. The structure of complex [Cu(L1)₂] consists of a discrete monomeric Cu(II) species stabilized by π-π stacking interactions involving the pyridyl and phenyl rings of the coordinated ligands. In contrast, in the case of complex [Cu(L2)]_n, each symmetrical  sulfonamide structure coordinates two Cu(II) ions, giving rise to a polymeric chain. Upon coordination, CuN₄ chromophores with the N-pyrydil atoms in trans position are generated, and the coordination geometry of both complexes can be best described as highly distorted square-planar. The ability of complex [Cu(L1)₂] to promote DNA cleavage with ascorbate activation was also evaluated; the complex has a moderate nuclease activity, being able to partially cleave supercoiled DNA to nicked circular and linear DNA. We herein also report the evaluation of the nuclease activity of complex Cu₂(N-(pyridin-2-yl)biphenyl-4-sulfonamidate)₄, previously characterized in terms of structure by our group.