胞嘧啶与金属离子Cu+／2+,Zn2复合物的稳定性研究

用M06/6-31+G*方法和PCM(polarized continuum model)溶剂模型研究了CnCu+/2+和CnZn2+配合物在气液两相中的稳定性顺序,重点从溶剂效应和电荷分布等方面讨论分析了与生物环境相关的液相中各配合物的稳定性。结果表明,CnCu+受溶剂效应和电子转移的影响不大,气液两相中最稳定的配合物均为C1Cu+,后面的配合物稳定性顺序基本一致;CnCu2+在气相中最稳定的也是C1Cu2+,受溶剂效应和电子转移的影响(溶液中C4CuII+→C4CuII2+过程比C1Cu+→C1Cu2+进程有更多的电荷转移(0.14 vs 0.07)),液相中最稳定的配合物变为C4CuII2+。CnZn2+在气液两相中最稳定的配合物均为C1Zn2+,这与CnCu+最稳定的配合物规律一致,但后面的配合物稳定性顺序变化较大,其中稳定性顺序中排第二位和第三位的配合物由气相中的C7ZnI2+和C6ZnI2+变为液相中的C4ZnII2+和C5ZnI2+。C4MII+/2+和C5MI+/2+因结构对称且电荷分布相似,稳定性基本一致。

A study of the stability of complexes formed by cytosine and metal ions(Cu+/2+,Zn2+)

The stability orders of CnCu+/2+ and CnZn2+complexes in both gas and liquid phases were studied by the M06/6-31+G* method and the PCM solvent model.Considering the solvent effect and charge distribution,all complexes stabilities in the liquid phase associated with the biological environment were analyzed.The results indicated that CnCu+was little affected by the solvent effect and electron transfer,and C1Cu+ the most stable complex in both gas and liquid phases.The stability order of other complexes changed little.The most stable complex of CnCu2+ was also C1Cu2+ in the gas phase,while in the liquid phase the most stable complex was C4CuII2+ because of solvent effect and electron transfer.The process of C4CuII+→C4CuII2+ transferred more electrons than that of the C1Cu+→C1Cu2+(0.14 vs 0.07) process in the liquid phase.The C1Zn2+ was the most stable complex in both gas and liquid phases.The stability order of complexes after C1Zn2+greatly changed.In the gas phase the second and the third stable complexes respectively were C7ZnI2+ and C6ZnI2+,while in the liquid phase this changed to C4ZnII2+ and C5ZnI2+.The relative stability of C4MII+/2+ was very close to that of C5MI+/2+because they had similar symmetrical structure and charge distribution.