田菁胶大分子的量子化学计算

Quantum Chemistry Calculation of Sesbania Gum Molecule

为了研究田箐胶大分子的化学反应活性与结构的关系 ,用GAMESS中MOPAC程序的PM3 方法在全局优化中确定了田菁胶大分子糖单元的几何构型和稳定构象 ,计算了该大分子绕两个旋转轴θ、φ旋转的势能面和羟基氧的电荷分布等数据 ,结果表明大分子基团之间不能绕θ、φ轴进行自由旋转 ,糖单元主链和侧链上的羟基均可进行取代反应 ,仅取代基几率分布存在差异 。

Quantum chemistry calculation by PM 3 method of MOPAC procedure is used to determine the geometric configuration and stable conformation of the structure unit of sesbania gum molecule in the global optimization. The potential surfaces of SG rotating about θ and φ axes and the charge distributions of hydroxyl oxygen atoms have been calculated by the PM 3 method. The results show that the gigantic groups of SG can not rotate about θ and φ axes freely. Meanwhile, the calculate results, which are in accord with the experimental data, explained the difference from the probability of substitute groups and the substitution reaction can take place in both of the main chain and side chain of the SG unit.