MOR分子筛对赖氨酸分子手性转变反应的限域催化

Confined Catalysis of MOR Molecular Sieve on Chiral Transition Reaction of Lysine Molecule

采用组合的量子化学ONIOM方法,研究MOR分子筛12元环孔道对赖氨酸分子手性转变反应的限域催化.结果表明:限域在MOR分子筛12元环孔道的客体与裸环境下的构象不同,过渡态a_TS2@MOR的1C—5N键长缩短,中间体SINT1@MOR的12H与9O,11H与9O以及12H与10O间的距离缩短;手性转变反应有a,b,c 3个通道;通道a为手性转变反应的主反应通道,决速步骤的Gibbs自由能垒为229.7kJ/mol,比裸反应决速步骤的Gibbs自由能垒252.6kJ/mol明显降低,即MOR分子筛对赖氨酸分子的手性转变反应有一定的限域催化作用.

We studied confined catalysis of the MOR molecular sieve 12-ring pore on the chiral transition reaction of lysine molecule by using the combined quantum chemistry ONIOM methods. The results show that conformations of the objects which confined in the MOR molecular sieve 12-ring pore are different from that in nude environment, the 1C-5N bond length of transition state a_TS2@MOR has been shortened and the distances of the intermediate SINTI@MOR between 12H and 9O, 11H and 9O as well as 12H and 10O have also been shortened. There are three channels a,b and c in chiral transition reaction. The channel a is the dominant reaction channel of chiral transition reaction, and the Gibbs free energy barrier of the step-determining step is 229. 7 kJ/mol, which is significantly lower than that of the Gibbs free energy barrier 252.6 kJ/mol, i. e. , the MOR molecular sieve has a confined catalytic effect on the chiral transition reaction of lysine molecule.