Theoretical study on relations between the helix structure and optical rotation of alanine

Abstract

: Seven possible pairs (R and S) of alanine conformers, both in the gaseous phase and in the aqueous solution, have been optimized at the computational level of B3LYP/6-311++G(2d,2p). And in the aqueous phase the polarizable continuum model has been used in the optimization. The geometry parameters have been discussed in details. The optical rotations of all the conformers have been calculated using B3LYP method of density functional theory at the basis sets of 6-311++G(2d,2p) and aug-cc-pvdz. The relations between the optical rotations and helical structures in the molecule conformers have been discussed theoretically, and arrived at a conclusion that just the helical structure in the molecule has made the chiral molecule have the property of the optical rotation.