A novel ruthenium polypyridyl complex of [Ru(bpy) 2(FcIP)](PF 6) 2(bpy=2,2′-bipyridine, FcIP=2-ferrocenyl-imidazo[4,5-f]-1, 10-phenanthroline) was synthesized and characterized by elementary analysis and 1H NMR. The binding of the complex to calf thymus(ct) DNA was investigated with absorption and luminescence spectroscopy titrations, steady-state emission quenching, and viscosity measurements. The results suggest that the complex acted as a ct-DNA intercalator with an intrinsic binding constant of (2.0±0.4)×10 5 L/mol in buffered 50 mmol/L NaCl.
A new ruthenium（Ⅱ） complex,[Ru（bpy）2bdpq](ClO4)2,where bpy=2,2′-bipyridine,（bdpq=2-（benzoxazol-2-yl）-dipyrido） [2,3-f: 2′,3′-h]quinoxaline,was synthesized and characterized by IR,（）1H NMR,MALDI-TOF MS,and elemental analysis.The electronic absorption and emission spectral titrations with calf thymus DNA,steady-state emission quenching by [Fe（CN）6]4-,and viscosity measurements were carried out to study the binding of [Ru（bpy）2bdpq](ClO4)2 with the DNA.The results indicate that the（Ru（Ⅱ）） complex acts as a DNA intercalator with a binding constant of（1.9±0.1）×106 L/mol at 50 mmol/L NaCl,and can serve as a good "DNA molecular light switches" with a luminescence enhancement factor of 180.
The dimerization of a well-known DNA light-switch [Ru(phen)2dppz]2+(phen=1,10-phenanthroline, dppz=dipyrido[3,2-a:2′,3′-c]phenazine), and its effect on calf thymus binding properties were studied by UV-Vis and emission spectroscopy in Tris-HCl buffered 50 mmol/L NaCl(pH=7.1). The results show that the complex has a strong tendency to dimerize with a dimerization constant of (1.8±0.3)×106 L/mol at the same order of magnitude as the DNA binding constant of (6.0±1.2)×106 L/mol for the Ru(Ⅱ) complex dimer, but one order of magnitude less than (4.9±1.5)×107 L/mol for the Ru(Ⅱ) complex monomer. This study has provided insight into a fundamental but important issue that should be taken into account for the DNA binding studies.
