Induction of Cholesteric Liquid Crystal by Helical Supramolecular Polymer

Abstract

Benzene tricarboxamide derivatives with long alkyl side chains are known to self-assemble into one-dimensional supramolecular polymers in solution. When their side chains bear stereogenic centers, supramolecular polymers with a one-handed helical geometry could result under appropriate conditions. Thanks to chiral amplification, one may achieve the one-handed helical geometry from optically antipodal mixtures of monomers or even from achiral monomers upon mixing with a small amount of their chiral versions. We envisioned that those self-assembling chiral motifs might provide a new possibility as chiral dopants for generating a cholesteric phase from a nematic phase. When a nematic liquid crystal was mixed with a self-assembling chiral dopant, it showed a characteristic texture for a cholesteric phase by polarized optical microscopy. Furthermore, Grandjean-Cano wedge method, together with infrared spectroscopy, allowed us to confirm that its ability to induce the cholesteric phase is enhanced along with the formation of helical supramolecular polymers.