Dna Photocleavage By Non-Innocent Ligand-Based Ru(Ii) Complexes

In this work, we demonstrate for the first time that [Ru(bpy)(2)(R-OQN)](+) complexes (bpy = 2,2'-bipyridine, R-OQN = 5-chloro-8-oxyquinolate or 5-bromo-8-oxyquinolate) are able to generate hydroxyl radicals and cleave DNA effectively upon visible light irradiation. The potent electron-donating ability of the R-OQN-based non-innocent ligands gives the complexes a high reducing capability, favoring the generation of superoxide anion radicals from which hydroxyl radicals may be generated. More interestingly, halogen substitution plays an important role. When the 5-Cl- or 5-Br-8-oxyquinolate ligand is replaced by 8-oxyquinolate or 5-CH3-8-oxyquinolate, the corresponding complexes lose their hydroxyl radical-generation and DNA photocleavage abilities. These findings open new applications for the non-innocent ligand-based Ru(II) complexes in the fields of biology and medicine, such as in photodynamic therapy (PDT).