DNA binding and nuclease activity of copper(II) complexes of tridentate ligands

► The DNA interactions of two copper(II) complexes have been studied. ► They show binding affinity to CT DNA with binding constant (Kb) values in the order of 105 M−1. ► Thermal denaturation and circular dichroism studies suggest groove binding of the complexes to CT DNA. ► They also exhibit strong DNA cleavage activity in presence of reducing agents. ► Mechanistic studies reveal the involvement of reactive hydroxyl radicals for their DNA cleavage activity.