Chirality Assignment of Amines and Amino Alcohols Based on Circular Dichroism Induced by Helix Formation of a Stereoregular Poly((4-carboxyphenyl)acetylene) through Acid−Base Complexation

An optically inactive polyacetylene, poly((4-carboxyphenyl)acetylene) (poly-1), exhibits an induced circular dichroism (ICD) in the UV−visible region upon complexation with chiral amines and amino alcohols in DMSO and in the film, the sign of which reflects the stereochemistry including bulkiness, type (primary, secondary, or tertiary), and absolute configuration of the amines. Therefore, the polyacetylene can be used as a novel probe for determining the chirality of amines. Most primary amines and amino alcohols of the same configuration gave the same sign for the induced Cotton effect; however, secondary and/or tertiary amines used in the present study tended to show Cotton effect signs opposite to those of the primary amines and amino alcohols of the same configuration. The magnitude of the ICD likely increases with an increase in the bulkiness of the chiral amines. The complexation dynamics during the formation of the helical structure of poly-1 with chiral amines were investigated on the basis of the...