Abstract:

The chiral transition mechanism of α-Ala molecule based on amino group as H transfer bridge confinement in the complex environment of SWBNNT (10,5) and water was studied by the combined method of quantum mechanics and molecular mechanics ONIOM(MP2/6311++G(3df,3pd): UFF)//ONIOM(B3LYP/6-31+G(d,p): UFF). The results show that there are two shift reaction channels a and b. Reaction channel a used amino group  a H transfer bridge and b used carbonyl and amino group as H transfer bridge, while H transfer was achieved by one or two water molecules as a medium; the highest energy barrier of a channel was obtained in the transition state where H was transfered from the chiral carbon to amino group. The high energy barrier reduced to 126.5 kJ/mol using two water molecules as  H transfer bridge, which is far less than the energy barrier 266.1 kJ/mol of the monomer in
the channel. The highest energy barrier of b channel was obtained in the transition state where H was transfered from the chiral carbon to carbonyl. The high energy barrier reduced to 155.6 kJ/mol using two water molecules as  H transfer bridge, which is far less than the energy barrier 319.9 kJ/mol of the monomer in the channel. That is to say the complex environment of SWBNNT (10,5) and water has a better catalytic action for the chiral transition of α-Ala molecule.

Key words: boron nitride nanotubes, α-Ala, chiral transition; , perturbation theory, transition state