Induced Circular Dichroism of β-Cyclodextrin Complexes with Substituted Benzenes

Abstract

The induced circular dichroism (ICD) of β-Cyclodextrin(β-CDx)-substituted benzene complexes was investigated. We observed the ICD on the absorption bands of achiral substituted benzene molecules, which is considered to be induced by the dissymmetric field of the chiral β-CDx host molecule. The electronic transitions which are polarized along the long axis of the substituted benzenes showed positive ICD, while the sings of the ICD of short-axis polarized transitions are negative. The rotational strengths of these inclusion complexes were calculated by the Kirkwood-Tinoco expression. From the comparison between the experimental and calculated results, it is concluded that these β-CDx complexes favor the axial inclusion in which the long axis of the substituted benzenes is parallel to the axis of the β-CDx cavity.