水环境下甲硫氨酸混合体系手性转换反应物的电子激发特性

Electronic Excitation Characteristics of Chiral Conversion Reactantsof Methionine Mixed System in Water Environment

用密度泛函理论(DFT)中的B3LYP方法,在6-311+G(2 df)基组水平上优化气相条件下甲硫氨酸(Met)分子的几何构型,并在PBE0/def2-TZVPP下,用含时密度泛函理论(TDDFT)方法计算得到隐式溶剂甲醇下Met与H_(2)O分子以1∶1和1∶2混合体系手性转换反应物的分子轨道(MO)特征及空穴-电子分布等值面图,并用图解对比分析电子激发特性.结果表明:三者定性分析结果基本一致,其中S-Met-CH_(3)OH与S-Met-CH_(3)OH+1H_(2)O和S-Met-CH_(3)OH+2H_(2)O的激发态S9定性结果不一致,S-Met-CH_(3)OH+2H_(2)O与S-Met-CH_(3)OH+1H_(2)O的激发态S7定性结果不一致;水链对S-Met-CH_(3)OH分子体系的电子激发特性有一定影响.

Using B3LYP method of density functional theory(DFT),the geometry of methionine(Met)was optimized under the gas phase condition at the level of 6-311+G(2 df)basis set,and under the PBE0/def2-TZVPP,using the method of time-dependent density functional theory(TDDFT),we obtained the molecular orbital(MO)characteristics,and hole-electron distribution isosurface maps of the chiral conversion reactants of Met and H_(2)O molecules with 1∶1,1∶2 mixed system in the implicit methanol solvent,compared and analyszed electronic excitation characteristics with diagrams.The results show that the three qualitative analysis results a re basically consistent,and the qualitative results of excitaed state S9 of S-Met-CH_(3)OH are inconsistent with those of S-Met-CH_(3)OH+1H_(2)O and S-Met-CH_(3)OH+2H_(2)O,the qualitative results of excited state S7 of S-Met-CH_(3)OH+2H_(2)O and S-Met-CH_(3)OH+1H_(2)O are inconsist ent,and the water chain has a certain effect on the electronic excitation characteristics of S-Met-CH_(3)OH molecular system.