Effect of DNA on the rate of electron transfer reactions between non-intercalated reactants: kinetic study of the reactions [Ru(NH3)5pz]2++[Co(C2O4)3]3- and [Ru(NH3)5py]2+ +[Co(NH3)4pzCO2]2+ in aqueous solutions in the presence of DNA

The kinetics of the electron transfer reactions between pentaammine(pyrazine)ruthenium(II), [Ru(NH3)5pz]2+ and tris(oxalate)cobalt(III), [Co(C2O4)3]3− and pentaammine(pyridine)ruthenium(II), [Ru(NH3)5py]2+ and tetraammine(pyrazinecarboxylate)cobalt(III), [Co(NH3)4pzCO2]2+ have been studied in aqueous solutions of DNA over the concentration ranges 0 to 2.46 × 10−3 mol dm−3 and 1.23 × 10−4 to 1.00 × 10−3 mol dm−3, respectively. The results are interpreted on the basis of a modified pseudophase model which takes into account the anticooperative character of the binding of the cationic reactants to DNA.