The chiral transition mechanism of α-alanine confined in the armchair SWBNNT (9

9)/water complex environment was studied using the method of quantum chemistry (ONIOM(B3LYP/6-311++G(3df

3pd):UFF)∥ ONIOM(B3LYP/6-31+G(d

p):UFF)) in the paper. The result indicated that

compared s-type α-Ala and intermediate INT1 in the SWBNNT(9

9)/water complex environment with monomer molecules

the bond lengths between oxygen and hydrogen

as well as carbon and hydrogen involving hydrogen transfer were all slightly increased. However

the distance between oxygen and hydrogen was significantly shorten under the same condition. It was found that there were four reaction paths in SWBNNT(9

9). Furthermore

the processes of hydrogen transfer were all realized by the way which made one or two water molecules as bridge. The maximum energy barriers of every path were always coming from transition state where hydrogen transferred from chiral carbon to carbonyl through measurement of the potential energy surfaces of chiral reaction. The minimum of maximum energy barriers was 153.8 kJ·mol

-1

 in the process that Amino heterogeneous firstly

then successively hydrogen transferred inside the carboxyl and hydrogen transferred from chiral carbon to carbonyl oxygen through two water molecules as bridge. Corresponding to chiral transition of α-Ala in SWBNNT(9

9) only

the minimum of maximum energy barriers was 302.7 kJ·mol

-1

 which obviously reduced. Moreover

corresponding to chiral transition of αAla in water environment only

the minimum of maximum energy barriers was 167.8 kJ·mol

-1

 that also reduced. The results showed that the SWBNNT(9

9)/water complex environment provided a preferable catalytic action for chiral transition of α-Ala.