Analytical Sciences

Interaction ofBis(ethylene)tin(bis(salicylidene)ethylenediamine) with DNA

Guo-Dong LIU,* Jian-Pei LIAO,** Yu-Zhi FANG,* Sha-Sheng HUANG,**Guo-Li SHENG,** and Ru-Qin YU**

*Department of Chemistry, East ChinaNormal University, Shanghai, 200062, P. R. China
**College of Chemistryand Chemical Engineering, Hunan University, Changsha, 410082, P. R.China

The fluorescence spectral characteristicsand interaction of bis(ethylene)tin(bis(salicylidene)ethylenediamine)[Et₂Sn(salen)] with DNA are described. The polarity of thesolvent has a strong effect on the fluorescence characteristics ofEt₂Sn(salen). Et₂Sn(salen) bound to DNA showed amarked decrease in the fluorescence intensity with a bathochromic shift ofthe excitation and emission peaks. A hypochromism in the UV absorptionspectra was also observed. KI quenching and competitive binding to DNAbetween Et₂Sn(salen) and ethidium bromide (EB) were studied inconnection with other experimental observations to show that theinteractive model between Et₂Sn(salen) and DNA is anintercalative one. The pH and salt effect on the fluorescence propertieswas also investigated. The intrinsic binding constant was estimated to be1.071 x 10⁵ mol L^-1 in base pairs and the bindingsite number is 1.98, respectively. A linear relationship betweenF/F₀ and the concentration of calf thymus DNAcovers 5.1 x 10^-6 - 2.41 x 10^-4 mol L^-1,which can be utilized for determining traces of calf thymus DNA with adetection limit of 1.1 x 10^-7 mol L^-1 in basepairs.

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