水液相下两性α-Ala与Na^(+)配合物旋光异构的理论研究  

Theoretical study on the optical isomerization of amphotericα-alanine and Na^(+)complexes in water-liquid phase environment

作　　者：赵宇 刘芳[2] 柯卓锋 刘军 高峰[2] 马宏源[2] 王佐成[2] ZHAO Yu;LIU Fang;KE Zhuofeng;LIU Jun;GAO Feng;MA Hongyuan;WANG Zuocheng(College of Computer Science,Baicheng Normal University,Baicheng 137000,China;College of Physics,Baicheng Normal University,Baicheng 137000,China;School of Materials Science&Engineering,Sun Yat-sen University,Guangzhou 510275,China)

机构地区：[1]白城师范学院计算机科学学院,吉林白城137000 [2]白城师范学院物理学院,吉林白城137000 [3]中山大学材料科学与工程学院,广东广州510275

出　　处：《中山大学学报（自然科学版）（中英文）》2021年第5期141-151,共11页Acta Scientiarum Naturalium Universitatis Sunyatseni

基　　金：吉林省教育厅科学研究规划项目(JJKH20210010KJ);吉林省自然科学基金(20160101308JC)。

摘　　要：采用密度泛函理论的M06-2X方法,结合自洽反应场理论的SMD模型方法,研究了水液相下两性S型α-丙氨酸与钠离子配合物(S-α-Ala·Na^(+))的旋光异构。研究发现:S-α-Ala·Na^(+)的旋光异构有a、b和c 3个通道,a通道是两性S-α-Ala·Na^(+)异构成中性S-α-Ala·Na^(+)后,质子以氨基氮为桥迁移;b通道是质子只以羰基氧为桥迁移;c通道是α-氢迁移到羰基氧后,质子再从质子化氨基迁移到α-碳。势能面计算表明:隐性溶剂效应下,a通道具有优势,决速步能垒是234.8 kJ·mol^(-1);b和c通道处于劣势,具有共同的决速步能垒均267.9 kJ·mol^(-1)。显性溶剂效应下,a通道变为劣势通道,决速步能垒为155.9~156.5 kJ·mol^(-1);b和c通道略具优势,决速步能垒为132.2~138.6 kJ·mol^(-1)。结果表明:水液相下丙氨酸钠配合物只能以极慢的速度消旋。The optical isomerization of amphoteric S-α-Ala·Na^(+)in water-liquid phase environment was investigated by using the M06-2X method based on density functional theory and the SMD model method based on self consistent reaction field(SCRF)theory.The results showed that the optical isomerization of S-α-Ala·Na^(+)has three channels a,b and c.In channel a,the proton transfers with amino nitrogen as a bridge after the isomerization of amphoteric S-α-Ala·Na^(+)to neutral S-α-Ala·Na^(+).And the proton is transferred merely using carbonyl oxygen as a bridge in channel b.In channel c,the proton transfers toα-C from protonation amino afterα-H is transferred to carbonyl oxygen.The potential energy surface showed that the channel a has the most advantage under the effect of recessive solvent and the energy barrier of the rate-determining step is 234.8 kJ·mol^(-1);While channel b and c had a disadvantage,they both have the common energy barrier of the rate-determining step about 267.9 kJ·mol^(-1).Under the effect of explicit solvent,channel a turned to an inferior channel,and its energy barrier of the rate-determining step is between 155.9 and 156.5 kJ·mol^(-1);channel b and c have a slight advantage and the energy barrier of the rate-determining step is between 132.2 and 138.6 kJ·mol^(-1).The results showed thatα-alanineNa(I)complex could only racemize at an extremely slow speed in the water-liquid environment.

关 键 词：Α-丙氨酸 钠离子 旋光异构 密度泛函理论 自洽反应场理论 过渡态 能垒 

分 类 号：O641.12[理学—物理化学]