摘要
用量子化学ONIOM(MP2/6-311++G(3df,3pd):UFF)//ONIOM(B3LYP/6-31+G(d,p):UFF)方法,研究了在SWBNNT(10,6)与水复合环境下α-Ala的手性转变.分子结构计算表明:在SWBNNT(10,6)和水复合环境的反应物S型α-Ala及中间体INT1与单体比较,实现氢转移要断的O-H和C-H键长略长,H与其要转移到的目标原子O的距离短很多.反应通道研究发现:在SWBNNT(10,6)与水复合环境的α-Ala手性转变反应有3条路径,氢转移都能以1个或2个H2O为媒介实现.势能面计算发现:手性转变过程中的最高能垒均来自H从手性C向羰基O转移的过渡态;在羧基内和从手性C向羰基O的H转移顺次实现的路径上,以2个H2O为氢转移媒介时最高能垒被降到最小,最小值为151.0 kJ·mol-1.比只在SWBNNT(9,9)内的302.7kJ·mol-1明显降低,比只在水环境的167.8kJ·mol-1也有所降低.研究还发现:氧自由基和氢氧根分别与水分子构成的链,使羧基内的H迁移变成了无势垒过程.结果表明:SWBNNT(10,6)与水的复合环境,对α-Ala实现手性转变具有较好的催化作用.
Using the quantum chemistry ONIOM （MP2/6-311＋＋G（3df,3pd） ：UFF）//ONIOM（B3LYP/6-31＋G （ d, p） ： UFF） method, the chiral transition mechanism of α-alanine confined in the ehiral helicity SWBNNT（10,6） / water complex environment is studied. The research on the molecular structure shows that, compared s-type α-Ala and the intermediates INT1 in the SWBNNT（10, 6）/water complex environment with monomer molecules, the bond lengths between oxygen and hydrogen, carbon and hydrogen involving hydrogen transfer are slightly increased. However, the distance between oxygen and hydrogen is significantly shorten under the same condition. The research on the reaction channels of a-Ala chiral shift shows that, there are four reaction paths in SWBNNT （10,6）. What＇s more, the process of the hydrogen transfer are all realized by the way which makes one or two water molecules as bridge. The research on the potential energy surfaces of ehiral reaction shows that, the maximum energy barriers of every path are always coming from transition state where hydrogen transfers from chiral carbon to carbonyl. The minimum of maximum energy barriers is 151.0 kJ · mol-1 in this process Amino heterogeneous first then hydrogen transfers inside the carboxyl which using two water molecules as bridge. It is obsviously decreased comparing with 302. 7 kJ · tool-1 in SWBNNT（9,9）, and it has a reduction to some extent in comparison to 167. 8 kJ · mo1-1 in the water solution. The research found： the chain composed of the Oxygen free radicals and hydroxyl with water molecules, respectively, made the hydrogen transfers inside the carboxyl into no barrier the process. The results show that chiral helicity SWCNT is better nanoreactor than armchair SWCNT for α-Ala.
出处
《复旦学报（自然科学版）》
CAS
CSCD
北大核心
2015年第4期529-540,共12页
Journal of Fudan University：Natural Science
基金
吉林省科技发展计划项目(20130101131JC)
关键词
氮化硼纳米管
Α-丙氨酸
手性转变
ONIOM方法
密度泛函
过渡态
boron nitride nanotubes
α-alanine
chiral transition
ONIOM method
density functional theory
transition state
