Particle dispersion system consisting of helically assembled liquid crystalline poly(para-phenylene)derivatives with reproducible chiroptical properties

Abstract

Liquid crystalline poly(para-phenylene) [LC-PPP] derivatives bearing a cyanobiphenyl moiety on the side chain and axially chiral binaphthyl derivatives were synthesized. To prevent artefacts arising from intrinsic anisotropies of the main and side chains of the LC-PPP derivative in circular dichroism (CD) and circularly polarized luminescence (CPL) spectra, a particle dispersion system was constructed from an LC-PPP derivative and an axially chiral binaphthyl derivative as a chiral dopant. Use of this particle dispersion system resulted in good reproducibility for chiroptical measurements and no discernible artefacts in either the CD or CPL spectra, enabling us to quantitatively analyse the chiroptical properties of the LC-PPP derivative. We elucidated the overall mechanism by which the axially chiral binaphthyl dopant induced helicity in the LC-PPP derivative.