Abstract
A new chiral compound was synthesized based on L-borneol. A cholesteric liquid crystal (LC) electrolyte solution was prepared by adding it as a chiral inducer to a nematic LC. A chiral poly(3,4-ethylenedioxythiophene) (PEDOT*, * = asymmetry) film was prepared by electrochemical polymerization in the induced cholesteric LC. The PEDOT* film showed a maximum absorption band due to a π–π* transition in the UV-vis absorption and bisignate Cotton effect in the reduced state in circular dichroism (CD). The CD spectrum indicates that PEDOT* backbones form right-handed helical aggregation. However, the maximum optical absorption band due to π–π* transition of the PEDOT* decreases and a new absorption band appears at long wavelengths upon oxidation due to generation of polarons as charge carriers. Bisignate Cotton effect disappears and broadly negative CD signal appears at long wavelengths in the oxidized state.
Highlights
Chiral conjugated polymers have seen much attention for their properties and have been applied in optoelectronic devices [1]
Bisignate Cotton effect disappears and broadly negative circular dichroism (CD) signal appears at long wavelengths in the oxidized state
The bisignate Cotton effect, exhibiting positive to negative signals at long wavelength can be due to Davydov splitting, indicate that the PEDOT* backbones form right-handed helical aggregation, likely produced by transcription from the asymmetric helical form of the matrix cholesteric liquid crystal (LC) prepared with the chiral inducer
Summary
Chiral conjugated polymers have seen much attention for their properties and have been applied in optoelectronic devices [1]. Since asymmetric electrochemical polymerization has been found, electrochemical polymerizations of achiral monomers in cholesteric liquid crystal (LC) (chiral nematic LC) have been performed [14]. Vortex poly(3,4-ethylenedioxythiophene) (PEDOT) films synthesized by electrochemical polymerization in chiral nematic LC was firstly carried out in 2009 [16]. This polymer film shows electrochemically driven change in optical rotation and circular dichroism. In order to increasing twisting power of the chiral inducer, we used 4-iodo benzoic acid. 4-iodo benzoic acid is expected to improve twisting power of the chiral inducer by three aspect:. We prepared a cholesteric LC electrolyte solution by using the bornyl-group-based chiral inducer.
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