Photoinvertible Chiral Liquid Crystal that Affords Helicity-Controlled Aromatic Conjugated Polymers

Photoinvertible chiral compounds are synthesized by linking a photoresponsive bisbenzothienylethene moiety with an axially chiral binaphthyl moiety and used as chiral dopants to prepare a photoinvertible chiral nematic liquid crystal (N*-LC) field. Subsequently, electrochemical polymerizations of ethylenedioxythiophene (EDOT) in the N*-LC field to synthesize helical poly(ethylenedioxythiophene)s (H-PEDOTs) are achieved. The H-PEDOTs show not only spiral morphologies resembling the fingerprinted texture of N*-LC in polarizing optical microscope but also bisignate Cotton effects in circular dichroism spectra, indicating the formation of a helically pi-stacked structure in terms of the main chains of H-PEDOT. In addition, the signs of the bisignate Cotton effect are strictly determined by the helicity of the N*-LC. The present N*-LC is the first reaction field exhibiting photoinvertible chirality with extremely high fatigue resistance and serves as an asymmetric medium for electrochemical polymerization, leading to dynamic helicity control of conjugated polymers.