Self-Assembled Helical Conjugated Poly(<i>m</i>-phenylene) Derivatives That Afford Whiskers with Hexagonal Columnar Packed Structure

Abstract

We have synthesized a series of π-conjugated polymers, poly( m -phenylene) [ PMP ] derivatives with chiral or racemic alkyl groups in side chains. Peculiar liquid crystalline phases or crystalline structures based on helical conjugated polymer main chains are elucidated. The PMP s synthesized by polymerizations of chiral and racemic monomers are found to self-assemble to form whiskers, so far as the polymers bear secondary alkyl groups with appropriate lengths in side chains. The whiskers have a hexagonal columnar packed structure, and the columns are uniaxially aligned parallel to the long axis of the whisker. The measurements of circular dichroism spectra and X-ray diffractions indicate that the polymers have a one-handed helical structure consisting of helicene-type conjugated main chains. The chiral PMP s show not only linearly polarized fluorescence after the macroscopic alignment but also circularly polarized fluorescence owing to the helical conjugated main chain.