Synthesis, DNA-binding, DNA-photocleavage and antioxidant activity of ruthenium(II) complex containing triazine ring ligand: [Ru(dmb)2(pdta)](ClO4)2

A new Ru(II) complex [Ru(dmb)2(pdta)](ClO4)2 (1) (dmb = 4,4′-dimethyl-2,2′-bipyridine, pdta = 3-(pyridine-2-yl)-as-triazino [5,6-f]-acenaphthylene) was synthesized and characterized by elemental analysis (EA), ES–MS, 1H NMR, UV–Vis and CV. The DNA-binding properties of complex 1 were investigated by absorption titration, thermal denaturation, viscosity measurement and photoactivated cleavage. The DNA-binding constant was determined to be 2.37 ± 0.14 × 105 M−1 (s = 1.90 ± 0.04) by electronic absorption titration, indicating that complex 1 interacts with DNA through intercalative mode. The redox peak potentials of this complex in CV were rationally assigned with the frontier molecular orbital stereographs resulting from the density functional theory (DFT) calculation. The photoactivated cleavage and cleavage mechanism of plasmid pBR322 DNA in the presence of complex 1 and various inhibitors were studied. The experiment for detecting the formation of singlet oxygen photo-sensitized by complex 1 was carried out, and the antioxidant activity of the Ru-complex and the ligand pdta against hydroxyl radical was also investigated.