布洛芬分子手性转变裸反应机理及水分子的催化作用——基于羰基和苯环作H迁移桥梁  

Bare reaction mechanism of chiral transition of ibuprofen molecules and the catalysis of water molecules using carbonyl and benzene ring as H transfer bridge

作　　者：高峰[1] 王佐成[1] 闫红彦[2] 杨晓翠[1] 佟华[1] 

机构地区：[1]白城师范学院物理学院,吉林白城137000 [2]白城师范学院计算机科学学院,吉林白城137000

出　　处：《中山大学学报（自然科学版）》2016年第6期115-124,共10页Acta Scientiarum Naturalium Universitatis Sunyatseni

基　　金：吉林省科技发展计划资助项目(20160101308JC)

摘　　要：采用基于密度泛函理论的B3LYP方法和微扰理论的MP2方法,研究了布洛芬分子手性转变裸反应和水助质子从手性碳向羰基迁移的机理。分子结构分析表明:水助质子从手性碳向羰基迁移过程的8元环过渡态b TS2·2H_2O和10元环过渡态b TS2·3H_2O对应的氢键键角都远大于6元环过渡态b TS2·1H_2O;过渡态b TS2·2H2O的8元环结构基本共面,过渡态a_TS1·3H_2O和b TS2·3H_2O的10元环结构明显偏离平面。反应路径研究发现:标题反应有6条路径,分别是质子只以羰基氧、以甲基碳和羰基O及以羧基和苯环联合作桥,从手性C的一侧迁移到另一侧。势能面计算表明:质子以羧基和苯环联合作桥迁移的路径为优势反应路径,裸反应的决速步吉布斯自由能垒为287.1 k J·mol^(-1),2个水分子构成的链使决速步的吉布斯自由能垒降为144.9 k J·mol^(-1)。结果表明:布洛芬分子的手性转变存在多条可能的路径,水分子对布洛芬分子的H迁移异构反应有明显的催化作用,生命体内水分子的存在、温度的涨落、分子的频繁碰撞和某种酶的作用等综合因素,是导致左旋布洛芬旋光异构的原因。The bare reaction of chiral transition of ibuprofen molecules and the mechanism of water-assis-ted proton transfer from carbon to carbonyl were studied using the B3 LYP method of density functional theory and the MP2 method of perturbation theory.The molecular structure analysis showed that the hy-drogen bond angles corresponding to the eight membered ring transition state bTS2·2H2O,and the ten membered ring transition state bTS2·3H2O in the processes of water-assisted proton transfer from carbon to carbonyl were all much larger than that corresponding to the six membered ring transition state bTS2· 1 H2 O.Moreover the eight membered ring structure of transition state bTS2·2H2 O was almost coplanar, and the ten membered ring structure of transition state a_TS1·3H2O/bTS2·3H2O was obviously out of plane.The study on the reaction path showed that there were six paths in the title reaction,where respec-tively proton only using ketonic O or methyl C and carbonyl O or carbonyl and benzene ring as the transfer bridge from one side to the other of chiral C.Calculations of potential energy surface showed that the path using proton was the dominant reaction channel,and carbonyl and benzene ring as the transfer bridge was the dominant reaction path.The Gibbs free energy barrier of the rate-determining step of bare reaction was 287.1 kJ·mol^-1 ,which would be reduced to 144.9 kJ·mol^-1 because of the chains constituted by two water molecules.The results showed that the chiral transition of ibuprofen molecules could be realized in multiple paths and the water molecules had a better catalysis on H transfer heterogeneous reaction of ibuprofen molecules,as well as the presence of water molecules in the body of a life,temperature fluctua-tions,molecular frequent collisions and the action of some enzyme conditions were the cause of S-Ibu op-tical isomers.

关 键 词：手性 布洛芬 密度泛函理论 过渡态 微扰理论 吉布斯自由能 

分 类 号：O641.12[理学—物理化学]