Ruthenium(ii) arene complexes showing DNA photobinding: the role of the basicity of the monodentate ligand

Abstract

Herein, a series of Ru(arene) complexes, [(η⁶-p-cymene)Ru(bpy)(X)]²⁺ complexes (bpy = 2,2′-bipyridine, X = pyridine, diazine, pyrimidine, and pyrazine) was synthesized, and its photochemical and photobiological properties were carefully compared. It has been found that the basicity of the monodentate ligand has a significant impact on the ligand photodissociation and photobinding DNA abilities of the complexes. A decrease in the basicity of the monodentate ligand leads to a decrease in the electron donating ability of the monodentate ligand; this enhances the photoinduced DNA covalent binding capabilities of 1–4. The CCK8 assay suggests that 4 exhibits the most potent phototoxicity against human lung carcinoma A549 cells among the examined complexes. By changing the basicity of the monodentate ligand, the photobinding abilities increases from the complexes 1 to 4; this provides a good strategy for the development of more efficient metallodrugs with photoactivity.