Determination of DNA by Use of the Molecular “Light Switch” Complex of Ru(bipy)2(dppz)2+

 A novel fluorimetric method has been developed for selective determination of DNA with the molecular “Light Switch” complex of Ru(bipy)2(dppz)2+. The maximum fluorescence intensity was produced in the pH range of 9.3–11.5, with the maximum excitation and emission wavelength of 471.8 nm and 599.8 nm, respectively. Under the optimum conditions, the fluorescence intensity was in proportion to the concentration of DNA. The linear range for calf thymus DNA salmon sperm DNA and herring sperm DNA reaches from the limit of determination to 1.5 μg/mL. The limits of determination for calf thymus DNA salmon sperm DNA and herring sperm DNA are 3.3 ng/mL, 2.8 ng/mL and 4.4 ng/mL, respectively. When the proposed method was used to determine DNA in the presence of some coexisting substances, a satisfactory result was obtained.