DNA interaction of new copper(II) complexes with sulfonamides as ligands

New copper(II) complexes with sulfonamide ligands have been prepared and characterized. Sulfonamide ligands were prepared through a reaction between 8-aminoquinoline and either 2-mesitylene (Hqmesa), 4-tert-butylbenzene (Hqtbsa), or α-toluene (Hαqtsa) sulfonyl chlorides. The structural analysis carried out for complex [Cu(αqtsa)2] indicated that the local environment of the Cu(II) cation is between a square planar and a tetrahedral geometry, with stacking of the benzene rings of the sulfonyl ligands between neighbor molecules. Powder EPR spectra at room temperature gave rhombic spectra for the [Cu(αqtsa)2] and [Cu(qmesa)2] complexes and an axial spectrum for the [Cu(qtbsa)2] complex, probably due to the steric hindrance of the methyl groups. Complexes [Cu(αqtsa)2] and [Cu(qmesa)2] are artificial chemical nucleases that degrade DNA in the presence of sodium ascorbate. A study of the radical scavengers revealed that the ROS (reactive oxygen species) involved in the DNA damage were hydroxyl, singlet oxygen-like species, and superoxide anion.