非限域单体异亮氨酸分子的手性转变机制

Chiral Transition Mechanism of Non-restricted Area Monomer Isoleucine Molecule

基于密度泛函理论的B3LYP方法,在6-311+G(2df)基组水平上考察非限域条件下单体异亮氨酸分子的手性转变过程.通过寻找包括过渡态和中间体的反应过程各极值点结构,绘制非限域条件下完整的异亮氨酸分子手性转变路径反应势能面,并分析各极值点的几何及电子结构特性.结果表明:非限域条件下,S型异亮氨酸分子手性C上的H原子以羧基上的O原子为桥梁,转移至手性C原子的另一侧,实现了从S型到R型异亮氨酸分子的手性转变;非限域条件下,该路径有4个中间体和5个过渡态,最大反应能垒为325.824 6kJ/mol,来源于第二个过渡态TS2-S-Ile.

Using B3 LYP methods of density functional theory,we investigated the chiral transition process of non-restricted area monomer isoleucine molecule at the 6-311＋G（2df）basis set level.A complete chiral transition path reaction potential energy surface was drawn by looking for the extreme value point structures including the transition state and intermediate,and the geometry and electronic structure properties of extreme value points were also analyzed.The results show that the H atom on the chiral C atom of S-isoleucine molecule can transfer to the other side of the C atom via the O atoms of carboxyl atoms as a bridge,to achieve the chiral transition of isoleucine molecule from S-type to R-type.There are four intermediates and five transition states on this path under the condition of non-restricted area.The biggest reaction energy barrier is 325.824 6kJ/mol derived from the second transition state TS2-S-Ile.