Kazuo Akagi

Helical polyacetylene was synthesized under an asymmetric reaction field consisting of chiral nematic (N*) liquid crystals (LCs). The chiral nematic LC was prepared by adding a chiroptical binaphthol derivative as a chiral dopant to a mixture of two nematic LCs. Acetylene polymerizations were carried out using the catalyst titanium tetra-n-butoxide-triethylaluminum dissolved in the chiral nematic LC solvent. The polyacetylene film was shown by scanning electron microscopy to consist of clockwise

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTHelical Polyacetylene: Asymmetric Polymerization in a Chiral Liquid-Crystal FieldKazuo Akagi*View Author Information Department of Polymer Chemistry, Kyoto University, Katsura, Kyoto 615-8510, Japan* E-mail: [email protected]Cite this: Chem. Rev. 2009, 109, 11, 5354–5401Publication Date (Web):October 9, 2009Publication History Received19 May 2009Published online9 October 2009Published inissue 11 November 2009https://pubs.acs.org/doi/10.1021/cr900198khtt

An optically resolvable and thermally chiral‐switchable device for circularly polarized luminescence (CPL) is first constructed using a light‐emitting conjugated polymer film and a double‐layered chiral nematic liquid crystal (N*‐LC) cell. The double‐layered N*‐LC cell with opposite handedness at each layer is fabricated by adding each of two types of N*‐LCs into each of the cells, and the N*‐LCs consist of nematic LCs and chiral dopants with opposite chirality and different mole concentrations.

Abstract The circularly polarized luminescence (CPL) of chiral disubstituted liquid‐crystalline polyacetylene (di‐LCPA) can be dynamically switched and amplified from left‐ to right‐handed CPL and vice versa through the selective transmission of CPL across a thermotropic chiral nematic liquid crystal (N*‐LC) phase. By combining a chiral di‐LCPA CPL‐emitting film with an N*‐LC cell and tuning the selective reflection band of the N*‐LC phase to coincide with the CPL emission band, a CPL‐switchable

Abstract Novel multifunctional conjugated polymers, [poly( p ‐phenylene)s and poly(bithienylene‐phenylene)s with ( R )‐ and ( S )‐configurations], which have fluorescence, chirality, and photoresponsive properties, have been designed and synthesized. The polymers are composed of π‐conjugated main chains, where poly( p ‐phenylene) and poly(bithienylene‐phenylene) are fluorescence moieties, and the side chains of the photochromic dithienylethene moiety are linked with chiral alkyl groups. The poly

Cationic π-conjugated polymers form an interchain helically π-stacked assembly with anionic chiral compounds that is stabilized by both electrostatic and π-π interactions to hierarchically self-organize into a spherulite with a circularly polarized blue luminescence. To the best of our knowledge, this is the first example of a chiroptical spherulite that is hierarchically constructed from π-conjugated polymers.

A series of crown ether type binaphthyl derivatives (CEBDs) were synthesized and used as chiral dopants to induce chiral nematic (N*) liquid crystals (LCs). The twisting powers of the CEBDs for phenylcyclohexane (PCH)-derived nematic LCs were evaluated. It was found that the twisting powers of the CEBDs increased with decreasing ring size of the crown ether. Helical polyacetylenes were synthesized in the N*-LCs induced by the CEBDs. The relationship between the morphology of the helical polyacet

This tutorial review presents current progress in the synthesis of helical polyacetylene (H-PA) using a chiral nematic liquid crystal reaction field as an asymmetric polymerisation solvent. In addition, we review the morphology-retaining carbonisation for helical graphite using H-PA as a carbonisation precursor. Carbonisation of H-PA films, via iodine doping, is demonstrated to produce carbon and graphitic films bearing completely preserved morphologies and even helical nanofibril structures.

We review the recent progress in the field of helically assembled <i>π</i>-conjugated polymers, focusing on aromatic conjugated polymers with interchain helical <i>π</i>-stacking that exhibit circularly polarized luminescence (CPL). In Part 1, we discuss optically active polymers with white-colored CPL and the amplification of the circular polarization through liquid crystallinity. In Part 2, we focus on the stimuli-responsive CPL that results from changes in the conformation and aggregation sta

Abstract The helical structures and optoelectronic functions of conjugated polymers were dynamically controlled using an external force-responsive liquid crystal field, leading to cultivation and development of a novel research field named “Interdisciplinary Chemistry Based on Integration of Liquid Crystals and Conjugated Polymers”. First the external stimuli-responsive liquid crystal field was prepared to construct super-hierarchical helical structures of the conjugated polymers. Subsequently,

Axially chiral binaphthyl derivatives with highly twisting powers were synthesised by substituting phenylcyclohexyl (PCH) mesogenic moieties into 2,2′ positions or 2,2′,6,6′ positions of binaphthyl rings. The di‐ and tetra‐substituted binaphthyl derivatives were adopted as chiral dopants to induce chiral nematic liquid crystals (N*‐LCs). The helical twisting power (βM) of tetra‐substituted binaphthyl derivative, D‐3, having direct linkages between the PCH moieties and the binaphthyl rings at the

A chiral reaction field with thermally invertible helical sense enables control of the helicity of the reaction product, which is a central challenge in asymmetric synthesis that has yet to be overcome. A novel chiral compound comprising two types of chiral moieties with opposite helicities and temperature dependences is synthesized; this compound is added as a chiral dopant to a mixture of nematic liquid crystals to prepare a chiral nematic liquid crystal (N*-LC). The N*-LC containing the chira