Radical-induced DNA damage by cytotoxic square-planar copper(II) complexes incorporating o-phthalate and 1,10-phenanthroline or 2,2′-dipyridyl

► We discovered two new copper-based cytotoxic agents. ► These agents target DNA through noncovalent binding modes. ► They induce double-strand DNA breaks in cisplatin-resistant cancer cells. ► These compounds generate intracellular reactive oxygen species in cancer cells. ► Cytotoxicity is linked to the induction of double-strand DNA breaks.