Cholesteric Liquid Crystal Inductive Asymmetric Polymerization: Synthesis of Chiral Polythiophene Derivatives from Achiral Monomers in a Cholesteric Liquid Crystal

Inductive asymmetric polymerization from achiral monomers is achieved through the use of cholesteric liquid crystal as an asymmetric reaction solvent. The chirality of the polymers, which have no chiral substituent, is considered to derive from the asymmetry produced by the chiral liquid crystal media during polymerization. No chiral molecules reacted chemically with the monomer during polymerization, and the cholesteric liquid crystal acted solely as a physical reaction environment. Polymers without chiral centers exhibit exciton couple-type circular dichroism and circular polarized luminescence. The chirality of the polymer is due to chiral aggregation, which occurs during the propagation process in the cholesteric liquid crystal medium and which is locked by interchain interaction in the π-conjugated system. Heat treatment of the polymer causes disaggregation and loss of chirality. The present results demonstrate cholesteric liquid crystal inductive asymmetric reaction can be performed by polycondensation in π-conjugated systems

Cholesteric Liquid Crystal Inductive Asymmetric Polymerization: Synthesis of Chiral Polythiophene Derivatives from Achiral Monomers in a Cholesteric Liquid Crystal

Inductive asymmetric polymerization from achiral monomers is achieved through the use of cholesteric liquid crystal as an asymmetric reaction solvent. The chirality of the polymers, which have no chiral substituent, is considered to derive from the asymmetry produced by the chiral liquid crystal media during polymerization. No chiral molecules reacted chemically with the monomer during polymerization, and the cholesteric liquid crystal acted solely as a physical reaction environment. Polymers without chiral centers exhibit exciton couple-type circular dichroism and circular polarized luminescence. The chirality of the polymer is due to chiral aggregation, which occurs during the propagation process in the cholesteric liquid crystal medium and which is locked by interchain interaction in the π-conjugated system. Heat treatment of the polymer causes disaggregation and loss of chirality. The present results demonstrate cholesteric liquid crystal inductive asymmetric reaction can be performed by polycondensation in π-conjugated systems

Optically Active Electrochromism of Poly(3,4-ethylenedioxythiophene) Synthesized by Electrochemical Polymerization in Lyotropic Liquid Crystal of Hydroxypropyl Cellulose/Water: Active Control of Optical Activity

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in a water solution of hydroxypropyl cellulose (HPC) as a polymer lyotropic liquid crystal (LC) gives polyEDOT*/HPC hybrid (PEDOT*/HPC) as an optically active polymer. Circular differential interference contrast (C-DIC) microscopy of the polymer reveals a well-resolved ordered structure, and circular dichroism (CD) measurements indicate a Cotton effect for the polymer film. PEDOT prepared using this chiral nematic LC field exhibits good electrochemical stability and switching between a dark blue reduced state and sky blue oxidized state with corresponding changes in Cotton effect. The polymer thus shows “electrochiroptical effect”, such as optically active electrochromism, and repeating change in CD through electrochemical redox process. The proposed method represents a new technique for the preparation of chiral conducting polymer films

Optically Active Electrochromism of Poly(3,4-ethylenedioxythiophene) Synthesized by Electrochemical Polymerization in Lyotropic Liquid Crystal of Hydroxypropyl Cellulose/Water: Active Control of Optical Activity

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in a water solution of hydroxypropyl cellulose (HPC) as a polymer lyotropic liquid crystal (LC) gives polyEDOT*/HPC hybrid (PEDOT*/HPC) as an optically active polymer. Circular differential interference contrast (C-DIC) microscopy of the polymer reveals a well-resolved ordered structure, and circular dichroism (CD) measurements indicate a Cotton effect for the polymer film. PEDOT prepared using this chiral nematic LC field exhibits good electrochemical stability and switching between a dark blue reduced state and sky blue oxidized state with corresponding changes in Cotton effect. The polymer thus shows “electrochiroptical effect”, such as optically active electrochromism, and repeating change in CD through electrochemical redox process. The proposed method represents a new technique for the preparation of chiral conducting polymer films

Estimation of the helical twisting power of chiral inducers by time-dependent density functional theory (TD-DFT) for electrochemical polymerization in cholesteric liquid crystals

Five chiral compounds were designed and synthesized using the Mitsunobu reaction to act as chiral inducers (i.e., chiral dopants) for the transformation of a nematic liquid crystal (LC) (4-n-octoxy-4′-cyanobiphenyl) into a cholesteric LC. These chiral inducers contain two types of chiral alkyl chains with different kinds of achiral mesogenic cores (biphenylcarboxylate, biphenoxy, and cyanobiphenoxy). We observed that the achiral mesogenic cores affected the helical twisting power in terms of both induction strength and helicity (left-/right-hand introduction). All the ester type inducers exhibited a positive Cotton effect and right-hand helical twisting power (HTP). However, ethers exhibited a negative Cotton effect and left-hand HTP. The microscopic HTPs (βM) of these inducers demonstrate a linear relation with their optical activities (ellipticity near the absorption maximum). Further, the time-dependent density functional theory (TD–DFT) calculation using the B3LYP/6-311++G (d, p) method has been used to predict the circular dichroism spectra of these inducers. The predicted optical activity was observed to be in accordance with that observed in the experimental result. This study proposes a method for predicting the HTP of chiral inducers that can be applied to achieve polymerization in the reaction fields of cholesteric LCs.</p

Optically Active Electrochromism of Poly(3,4-ethylenedioxythiophene) Synthesized by Electrochemical Polymerization in Lyotropic Liquid Crystal of Hydroxypropyl Cellulose/Water: Active Control of Optical Activity

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in a water solution of hydroxypropyl cellulose (HPC) as a polymer lyotropic liquid crystal (LC) gives polyEDOT*/HPC hybrid (PEDOT*/HPC) as an optically active polymer. Circular differential interference contrast (C-DIC) microscopy of the polymer reveals a well-resolved ordered structure, and circular dichroism (CD) measurements indicate a Cotton effect for the polymer film. PEDOT prepared using this chiral nematic LC field exhibits good electrochemical stability and switching between a dark blue reduced state and sky blue oxidized state with corresponding changes in Cotton effect. The polymer thus shows “electrochiroptical effect”, such as optically active electrochromism, and repeating change in CD through electrochemical redox process. The proposed method represents a new technique for the preparation of chiral conducting polymer films

Optically Active Electrochromism of Poly(3,4-ethylenedioxythiophene) Synthesized by Electrochemical Polymerization in Lyotropic Liquid Crystal of Hydroxypropyl Cellulose/Water: Active Control of Optical Activity

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in a water solution of hydroxypropyl cellulose (HPC) as a polymer lyotropic liquid crystal (LC) gives polyEDOT*/HPC hybrid (PEDOT*/HPC) as an optically active polymer. Circular differential interference contrast (C-DIC) microscopy of the polymer reveals a well-resolved ordered structure, and circular dichroism (CD) measurements indicate a Cotton effect for the polymer film. PEDOT prepared using this chiral nematic LC field exhibits good electrochemical stability and switching between a dark blue reduced state and sky blue oxidized state with corresponding changes in Cotton effect. The polymer thus shows “electrochiroptical effect”, such as optically active electrochromism, and repeating change in CD through electrochemical redox process. The proposed method represents a new technique for the preparation of chiral conducting polymer films

Preparation of helical liquid crystal electrolyte with L-isoleucine derivatives and molecular asymmetric imprinting polymerization in liquid crystal to produce electro-optically coloration active polymers having chiral charge carrier chiralions

Molecular asymmetric imprinting polymerization in the cholesteric liquid crystal was carried out. An L-isoleucine derivative with fluorine was synthesized for a chiral inducer to induce the cholesteric liquid crystal from the nematic liquid crystal. A substance with multiple asymmetric centers can be obtained conveniently to use amino acid as chiral substance. The L-isoleucine derivative induced helical structure for 4-cyano-4'-hexylbiphenyl (6CB). Electrochemical preparation of π-conjugated polymers was carried out in the cholesteric liquid crystal. Fingerprint texture derived from the cholesteric liquid crystal was transcribed to the polymers. UV-vis and circular dichroism (CD) spectra of oxidized (doped) for and reduced (dedoped) form of the polymer were measured. Electrochemical polymerization in the helical liquid crystal produced the molecular aggregation imprinted chiral polymers, which have liquid crystal-like aggregation form, chirality with no stereogenic center via formation of polymer atropisomer, and electrochemical driven change in optical activity, as a form of electro-optically coloration active polymers. Finally, the polarons and bipolarons are in the form of chiral structure. These charge carriers in the polymers can be determined as chiral charge carrier “chiralions”.</p