气相和溶液中金属离子与腺嘌呤配位选择性的理论研究

在B3LYP/6-31G(d,p)水平,全优化Mg2+、Ca2+、Mn2+、Co2+、Zn2+、Cu2+、Ni2+、Cd2+ (用有效实势(ECP) 方法处理)与腺嘌呤(A) N(1)、N(7)位点配位的两类配合物气相结构,通过相互作用能和自由能分析分别得出两位点对所研究金属离子的选择性顺序;后采用Onsager模型,优化其在水溶液(=78.39)中的结构,讨论溶剂效应对上述顺序的影响;通过相对自由能分析分别得出气相和溶液中,同种金属对两位点的选择性规律。溶液中金属离子与N(7)位配位的相对优选顺序为:Co2+ > Mg2+ > Cd2+ > Ca2+ > Zn2+ > Mn2+ > Ni2+ > Cu2+。

Theoretical Study on the Coordination Selectivity between Metal Cations and Adenine in Gas and Solution

The interaction of adenine with Mg2 , Ca2 , Mn2 , Co2 , Zn2 , Ni2 , Cu2 and Cd2 cations were calculated with DFT/B3LYP method by using the standard 6-31G(d,p) basis set. Effective core potential (ECP) was used for Cd2 . The calculations of stabilities of the complexes in a polar medium have been performed with Onsager solvation model. All geometries were optimized without symmetry restrictions. The interaction energies and interaction Gibbs energies of complexes provide a comparatively reliable quantification of the selectivity of adenine for the studied metal ions not only in gas but also in the polar medium (water = 78.39), and relative interaction Gibbs energies of the isomers of the complexes have shown the selectivity of different metal-binding sites of the ligands as follows: Co2 >Mg2 >Cd2 > Ca2 >Zn2 >Mn2 >Ni2 >Cu2 .