Abstract
Two triazine-containing ruthenium(II) complexes, [Ru(dmb)2(pdpt)](ClO4)2 (dmb = 4,4′-dimethyl-2,2′-bipyridine, pdpt = 3-(pyridine-2-yl)-5,6-diphenyl-as-triazine) (1) and [Ru(dmb)2(pdtp)](ClO4)2 (pdtp = 3-(pyridine-2-yl)-as-triazino[5,6-f]phenanthrene) (2), were synthesized and characterized by elemental analysis, ES-MS, 1H NMR, UV-Vis spectra, and cyclic voltammetry; the crystal structure of 2 was determined by X-ray diffraction. DNA-binding behaviors of both complexes were studied by absorption titration, thermal denaturation, and viscosity measurements. The photoactivated DNA cleavage of plasmid pBR322 in the presence of 1 and 2 was explored through gel electrophoresis. Antioxidant activities of the two complexes against hydroxyl radical (•OH) were also investigated. The results indicate that the DNA-binding affinity of 2 is much greater than that of 1, and that 2 binds to calf thymus DNA by intercalation, but 1 binds in partial intercalation, with π–π stacking on the DNA surface. Experimental findings made through analysis of the CV, absorption spectra, X-ray crystal structure, and the DNA-binding properties were compared with those of theoretical studies using density functional calculations.
Acknowledgments
We are grateful to Shaoguan University for the financial support. We are indebted to Prof. K.C. Zheng (Sun Yat-sen University) for the good works on the DFT calculation, and we are grateful to Prof. Chao Hui (Sun Yat-Sen University) for his specific directions.