基于密度泛函理论的气相下α-Ala·Fe2+配合物手性转变机理

Chiral Transition Mechanism of Fe and α-Ala Complexes in Gas Phase Based on Density Functional Theory

采用密度泛函理论的M06和MN15方法,研究了两个S型α-丙氨酸分子(S-α-Ala1和S-α-Ala2)与Fe2+的配合物S-A1和S-A2的手性转变.研究发现:S-A1的手性转变可通过以氧、氮、铁、氧与氮联合以及氧与甲基碳联合为桥的氢迁移实现.S-A2的手性转变可通过打开螯合环接S-A1的异构实现,还可打开螯合环通过以氧、铁及氧与甲基碳联合为桥的氢迁移实现;还可通过羧基内氢迁移后,以羰基氧及羰基氧和甲基碳联合为桥的氢迁移实现.势能面计算表明:以铁为氢负离子迁移桥梁的S-A1和S-A2手性转变反应具有优势,活化自由能垒分别是235.0和204.4kJ·mol^-1左右.结果表明:α-Ala·Fe^2+配合物可以很好地保持其手性特征.

The chiral transition mechanism of S-α-Ala1 and S-α-Ala2 with Fe2+complexes(S-A1 and S-A2)have been studied using the M06 and MN15 methods based on density functional theory.The study shows that the chiral transformation of S-A1 can be achieved by H migration using O,N,Fe,the combination of O and N,and the combination of O and methyl C atom as a bridge.The chiral transformation of S-A2 can be achieved by opening the chelate ring to the isomerization of S-A1,and the chelate ring can also be opened by H migration using O,Fe,and the combination of O atom with methyl C atom as a bridge,and after the H migration in the carboxyl group,the H migration takes place as the bridge between the carbonyl O and the combination of the carbonyl O and the methyl C atom.Potential energy surface studies show that the chiral transition reactions of S-A1 and S-A2 with iron as a bridge for the migration of hydride ions have advantages with these activation energies are about 235.0 and 204.4 kJ·mol^-1,respectively.The results show that the alanine with Fe^2+ complexes can maintain its chiral characteristics well.