鸟嘌呤和次黄嘌呤的铜络合物的吸附作用和伏安特性研究

Adsorption and Voltammetric Characteristics of the Complexes of Copper With Guanine and Hypoxanthine

本文研究了鸟瞟呤(Gua)和次黄嘌呤(Hxa)铜络合物在悬汞电极(HMDE)上的吸附作用和电极反应机理,溶液中形成的1:1络合物有强烈吸附性,通过分子结构的比较,推断出Cu^(2+)与Gua和Hxa的咪唑环N(7)和外环氧O(6)原子结合形成封闭的五元环。嘌呤环的π-电子有使分子呈平面吸附的趋势,但是Gua络合物分子优先取“倾斜”定向;随着表面吸附浓度增加,Hxa络合物分子存在从“平面”向“垂直”的再定向作用。本文测定了单层吸附浓度、包含的电量和每个分子占据的面积。络合物吸附得到S形等温线,它与Frumkin吸附等温线接近。本文还列出有关吸附参数B、a、△G_A^O和θ~*的计算结果。

The interaction of guanine(Gua)and hypoxanthine(Hxa)with Cu2+ ions and the adsorption of the complexes at hanging mercury drop electrode are not only enable to elucidate the mechanism of the electrode process but also help to understand some informations of interaction between Cu2+and nucleic acids. The experimental results reveal that a complex with 1 : 1 coordination formed in solution is adsorbed at the electrode surface. The adsorbed monolayer is about 2. 88 and 1. 39 × 10-10mol/cm2,the quantity of charge involved in the formation of this layer is equated to 0. 501 and 0. 247 μC/cm2,the area occupied by one complex molecule of Gua and Hxa is 57. 7 A2 and 119. 5 A2,respectively. A S-shaped adsorption isotherm is determined for bases studied and it is good approximation to Frumkin isotherm.The adsorptive parameters,B,a,Δ^GA and θwere calculated.