Stereocontrolled Chiral Polymers

Nakano, T.; Okamoto, Y.

doi:10.1016/b978-0-444-53349-4.00175-8

Cited by 9 publications

(9 citation statements)

References 607 publications

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“…In other words, distance chirality of terminal optically active group in the mesogen induces main chain chirality. In the previous studies, main chain chirality of polymers was induced by chiral side chain located near position to the main chain, showing molecular functionalities [17][18][19][20][21][22][23]. The polymer prepared in this study is first founding in researches of aromatic LC conjugated polymers that the optically active group in the terminal induces main chain chirality from distance in molecular level.…”

Section: Optical Propertymentioning

confidence: 80%

Preparation of poly(thiophene-alt-pyrrole) bearing chiral LC group

Yatsu

Yonehara

Goto

2020

Polymer-Plastics Technology and Materials

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Preparation of poly(thiophene-alt-pyrrole bearing mesogen) was carried out with Migita-Kosugi-Stille coupling type polycondensation with an aid of Pd(0) complex catalyst. The resultant polymer shows lyotropoic liquid crystallinity with good film forming property.The smectic fan-shaped texture is maintained after completion of evaporation of solvent from the polymer solution. The cast film having LC (LC) order shows light emission function upon irradiation of excitation light at 460 nm. The polymer shows LC domain emission. Mechanical orientation allows to yield LC domain aligned film with band structure. Chiral mesogenic side chain induces π-conjugated main chain helicity from distance in molecular level.

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Section: Optical Propertymentioning

confidence: 80%

Preparation of poly(thiophene-alt-pyrrole) bearing chiral LC group

Yatsu

Yonehara

Goto

2020

Polymer-Plastics Technology and Materials

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“…The polymer obtained with CTA1 and (S)-2d was then analyzed by 1 H NMR and MALDI-TOF-MS (Figure 2). The proton signals ascribed to the repeating BzF units were relatively sharp, suggesting high stereoregularity, which will be discussed later.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The polymers obtained in toluene and CH 2 Cl 2 were analyzed in more detail by 1 H and 13 C NMR to clarify the stereostructures. The 1 H NMR spectrum of the polymers obtained in CH 2 Cl 2 showed broader peaks than those obtained in toluene (Figure 6A,B), indicating lower stereoregularity in CH 2 Cl 2 .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…6−9 However, these vinyl polymers rarely show optical activity, even if their asymmetric carbons are structured to have high isotacticity with only one type of chiral center consisting of consecutive R or S sequences. 1 This is because the whole polymer chain can be regarded as having a mirror plane, where the chain end groups are ignored due to the long polymer chains, i.e., the chiral center in the main chain is pseudoasymmetric. However, when the side chain has a very bulky substituent, the one-handed helical conformation of the main chain is conserved, resulting in optically active vinyl polymers as a special case.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Optically active natural macromolecules with highly controlled structures, such as proteins, deoxyribonucleic acids, and polysaccharides, possess unique and specialized functions that are indispensable for maintaining our lives. This constantly motivates research on the controlled synthesis of optically active polymers, which have unique structures and functions that can improve our modern life. − …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Asymmetric Cationic Polymerization of Benzofuran through a Reversible Chain-Transfer Mechanism: Optically Active Polybenzofuran with Controlled Molecular Weights

et al. 2022

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Benzofuran (BzF) is a prochiral, 1,2-disubstituted, unsymmetric cyclic olefin that can afford optically active polymers by asymmetric polymerization, unlike common acyclic vinyl monomers. Although asymmetric cationic polymerization of BzF was reported by Natta et al. in the 1960s, the polymer structure has not been clarified, and there are no reports on molecular weight control. Herein, we report dual control of the optical activity and molecular weight of poly(BzF) using thioether-based reversible chain-transfer agents for asymmetric cationic polymerization with β-amino acid derivatives as chiral additives and aluminum chloride as a catalyst. This asymmetric moderately living cationic polymerization leads to an increase in molecular weight and specific optical rotation with monomer conversion. In addition, asymmetric block polymers consisting of opposite absolute configurational segments were synthesized using both enantiomers sequentially as chiral additives. Finally, a comprehensive analysis of the polymerization products and the model reaction revealed that the optical activity of poly(BzF) originates from the threo-diisotactic structure, which occurs by regio-, trans-, and enantioselective propagation.

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Tricks of Light on Helices: Transformation of Helical Polymers by Photoirradiation

Nakano

2014

The Chemical Record

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The following polymer structural transitions were achieved using light: preferred-handed helix formation for poly(9,9-di-n-octylfluoren-2,7-diyl), helix racemization (helix-helix transition) for poly(2,7-bis(4-t-butylphenyl)fluoren-9-yl acrylate) and poly(2,5-bis[4-((S)-2-methylbutyloxy)phenyl]styrene), and helix decomposition for poly(2,7-bis(4-t-butylphenyl)-9-methylfluoren-9-yl acrylate) and poly(2,7-bis(4-t-butylphenyl)fluoren-9-ylmethyl methacrylate). Although these types of transitions and chemical transformations have been studied mainly using heat or chemicals as stimuli, light can also cause these structural alterations. In the helix construction and the helix-helix transition, a key transition is a twist-coplanar conformational change of a biphenyl or an aryl-aryl unit in the side chain or the main chain of the polymer. Furthermore, the helix-helix transition was caused only by light and not by heat. The examples discussed in this review are expected to trigger off a new direction in synthesis and reaction of chiral polymers.

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Stereocontrolled Chiral Polymers

Cited by 9 publications

References 607 publications

Preparation of poly(thiophene-alt-pyrrole) bearing chiral LC group

Preparation of poly(thiophene-alt-pyrrole) bearing chiral LC group

Asymmetric Cationic Polymerization of Benzofuran through a Reversible Chain-Transfer Mechanism: Optically Active Polybenzofuran with Controlled Molecular Weights

Tricks of Light on Helices: Transformation of Helical Polymers by Photoirradiation

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