Synthesis and Properties of Optically Active Polymenthoxyalkynes: II. Thermal and Chiroptical Properties

A group of optically active polymenthoxyalkynes is synthesized. Their thermal and chiroptical properties are investigated to gain information on the structure-property relationship of the chiral polymers. The polymerization of the functional menthoxyalkynes using WCl₆-Ph₄Sn as catalyst and 1,4-dioxane as solvent are fulfilled in high yields and polymers have relatively low PDI. The polymers and monomers exhibit strong Cotton effects but the former have higher molar ellipticity value. The polymenthoxyalkynes with a biphenyl moiety in the side chain intervening between the backbone and the chiral center has an induced circular dichroism arising from the twisted or helix structure of the backbone.