多巴胺DA分子的构象异构及其一水复合物的结构与性质

Conformation isomerization of DA and the characters of DA…H_2O complex

采用密度泛函B3LYP/6-31+G~#方法对多巴胺DA的构象异构及其稳定性进行了研究.结果表明,势能面上存在6种稳定构象和8种构象转换过渡态,构象之间主要通过C1—O7[二面角T_1:H15O7C1C6],C2—O8[二面角T_2:H16O8C2C3]和C9一C10[二面角T_3;N11C10C9C5]单键旋转而相互转化.频率及NBO分析表明,分子内存在红移O…H-O及蓝移N…H—C两类氢键,氢键中电子转移类型均为LP_1(X)→σ~#(H—Y)[X=O,N;Y=O,C],二级稳定化能E^((2))对稳定构象有3.6 kJ·mol^(-1)～9.3 kJ·mol^(-1)的稳定化贡献.分子中的原子理论(AIM)分析表明,构象中O…H一O及N…H—C键的电子密度ρ(r)和Laplacian量▽~2ρ(r)分别在0.0094～0.0171和0.0307～0.0798之间.采用极化连续模型(polarized continuum model,PCM)对体系进行了溶剂化效应计算,结果表明,DA的构象转换主要在水相中进行.应用静电势模型(electrostatic potential map,EPM)对构象的活性位点进行了预测,并以此研究了多巴胺一水复合物的结构与性质.

The DFT（B3LYP/6-31＋G ） method was used to study the conformations stable and isomerization of dopamine. The results show that there are six stable conformations and eight translate states on the energy surface. Conformations can be convert to the other by the rotation of the C1O7 [dihedral angle T1： H15O7C1C6], C2-O8 [dihedral angle T2： H16O8C2C3] and C9--C10 [dihedral angle T3： N11--C10--C99--C5] single bond. NBO analysis show that the O…H--O and N…H--C hydrogen bonds exist in the conformation and the electron transfer are all LP1 （X）→σ （H--Y）[X=O, N; Y=O, C] which provide 3.6 kJ . mol-1- 9.3 kJ .mol-1 energy to the corresponding conformation. The AIM results indicate that the ρ（r） and 2ρ（r） range at the hydrogen bond O…H--O and N…H--C BCP are 0.0094-0. 0171 and 0. 0307-0. 0798. The solvent effect have studied by polarized continuum model （PCM）. The calculated results implied that the conversion mainly occurred in the aqueous solution. Also, the electrostatic potential map （EPM） model was used to predict the active sites of AD and the characters of DA… H2O have studied.