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

Abstract

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.