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Jianping Deng - One of the best experts on this subject based on the ideXlab platform.

  • chiral Helical substituted polyacetylene grafted on hollow Polymer particles preparation and enantioselective adsorption towards cinchona alkaloids
    Polymer Chemistry, 2019
    Co-Authors: Xueyong Yong, Jianping Deng
    Abstract:

    Incorporating chiral Helical structures with porous architectures and/or functionalities in a single entity is a promising strategy, which may provide various advanced functional materials with potential applications that cannot be achieved in routine materials. In this contribution, hollow Polymer particles (HPPs) were constructed by biomass trans-anethole and maleic anhydride and employed as a unique support for grafting chiral Helical substituted polyacetylene. To prepare the designed chiral hollow particles, HPPs were firstly reacted with propargylamine to form HPPs simultaneously bearing carboxyl groups and Polymerizable alkynyl groups on the shell (the particles were named M-HPPs). After coPolymerizing the alkynyl groups tethered on M-HPPs with a chiral acetylenic monomer (M1, R or S), hollow particles grafted with chiral Helical Polymer chains were obtained. The resulting hollow particles exhibit fascinating optical activity and enantioselective adsorption capacity towards cinchona alkaloids, in which (+)-cinchonine/(−)-cinchonidine were used as chiral drug models. Taking advantage of the preparation strategy, a number of novel chiral hollow particles of the kind may be constructed next. They are anticipated to find wide applications in chiral-related areas.

  • seed surface grafting precipitation Polymerization for preparing microsized optically active Helical Polymer core shell particles and their application in enantioselective crystallization
    Macromolecular Rapid Communications, 2018
    Co-Authors: Biao Zhao, Jianping Deng
    Abstract:

    : Core/shell particles constructed by Polymer shell and silica core have constituted a significant category of advanced functional materials. However, constructing microsized optically active Helical Polymer core/shell particles still remains as a big academic challenge due to the lack of effective and universal preparation methods. In this study, a seed-surface grafting precipitation Polymerization (SSGPP) strategy is developed for preparing microsized core/shell particles with SiO2 as core on which Helically substituted polyacetylene is covalently bonded as shell. The resulting core/shell particles exhibit fascinating optical activity and efficiently induce enantioselective crystallization of racemic threonine. Taking advantage of the preparation strategy, novel achiral Polymeric and hybrid core/shell particles are also expected.

  • intense circularly polarized luminescence contributed by Helical chirality of monosubstituted polyacetylenes
    Macromolecules, 2018
    Co-Authors: Biao Zhao, Kai Pan, Jianping Deng
    Abstract:

    Introducing fluorescent chromophores to Helical architectures can generate circularly polarized luminescence (CPL). Herein, a series of fluorescent chiral Helical monosubstituted polyacetylenes showing both intense optical activity and CPL are prepared by coPolymerizing achiral fluorescent acetylenic monomer and a chiral monomer. The luminescence dissymmetry factor (glum) values of the obtained coPolymers can reach up to +0.136 and −0.264. The formation of predominantly one-handed Helical structures in the coPolymer backbones has proved to play crucial roles in achieving the intense CPL. The dynamic Helical Polymer chains further enable the CPL-active materials to exhibit both solvent sensitivity and temperature sensitivity. Moreover, the Helical Polymer structures can also helpfully restrain the aggregation-caused quenching (ACQ) effect of fluorescent groups. Therefore, the Helical Polymers play double roles: providing Helical chirality for generating CPL and simultaneously circumventing ACQ effect of ch...

  • Intense Circularly Polarized Luminescence Contributed by Helical Chirality of Monosubstituted Polyacetylenes
    2018
    Co-Authors: Biao Zhao, Kai Pan, Jianping Deng
    Abstract:

    Introducing fluorescent chromophores to Helical architectures can generate circularly polarized luminescence (CPL). Herein, a series of fluorescent chiral Helical monosubstituted polyacetylenes showing both intense optical activity and CPL are prepared by coPolymerizing achiral fluorescent acetylenic monomer and a chiral monomer. The luminescence dissymmetry factor (glum) values of the obtained coPolymers can reach up to +0.136 and −0.264. The formation of predominantly one-handed Helical structures in the coPolymer backbones has proved to play crucial roles in achieving the intense CPL. The dynamic Helical Polymer chains further enable the CPL-active materials to exhibit both solvent sensitivity and temperature sensitivity. Moreover, the Helical Polymer structures can also helpfully restrain the aggregation-caused quenching (ACQ) effect of fluorescent groups. Therefore, the Helical Polymers play double roles: providing Helical chirality for generating CPL and simultaneously circumventing ACQ effect of chromophores. The present study provides new insights into designing and preparing advanced functional chiroptical materials

  • Combining Chiral Helical Polymer with Achiral Luminophores for Generating Full-Color, On–Off, and Switchable Circularly Polarized Luminescence
    2018
    Co-Authors: Biao Zhao, Kai Pan, Jianping Deng
    Abstract:

    Circularly polarized luminescent (CPL) materials are currently drawing ever-increasing interest. This contribution reports the first success in simply combining chiral Helical substituted polyacetylenes (HSPAs) with achiral luminophores to fabricate CPL materials demonstrating a high dissymmetry factor (glum) up to 10–1, despite neither covalent nor noncovalent interactions occurring between the two components. Circularly polarized scattering and fluorescence-selective absorption mechanisms are proposed for the generation of CPL, and a “matching rule” is further established for selecting chiral Polymers and achiral luminophores for the purpose. Taking advantage of the circularly polarized scattering effect, full-color tunable CPL materials are prepared from the combination of achiral fluorescent dyes and chiral HSPAs. Following the fluorescence-selective absorption mechanism, functional composite films with on–off and switchable CPL performance are fabricated. Also, remarkably, the glum value in the prepared materials can reach up to +0.323. The present study provides a simple, powerful, and universal strategy for constructing novel CPL materials

Wantai Yang - One of the best experts on this subject based on the ideXlab platform.

  • emulsion coPolymerization of substituted acetylenes for constructing optically active Helical Polymer nanoparticles synergistic effects and helicity inversion
    Journal of Polymer Science Part A, 2016
    Co-Authors: Biao Zhao, Jianping Deng, Wantai Yang
    Abstract:

    CoPolymerizations of substituted acetylenes have been intensively studied in solution Polymerization for constructing chirally Helical Polymers, while emulsion coPolymerizations of the kind of monomers have been only scarcely reported. In the present study, chiral substituted acetylene monomer containing cholic acid group underwent emulsion coPolymerizations with an achiral acetylenic monomer in the presence of rhodium catalyst, providing optically active Helical coPolymer nanoparticles. Synergistic effects were found in the resulting Helical coPolymers, enabling one certain coPolymer to show the maximum CD signal intensity. Moreover, the helicity of the Helical coPolymers in nanoparticle state was opposite to that in solution state. This is the first demonstration that synergistic effects and helicity inversion simultaneously occurred in Helical coPolymers prepared by emulsion coPolymerization process. To deepen the understanding of the unique phenomena, corresponding solution coPolymerization and emulsification process were also investigated. Different from “Sergeant and Soldiers rule” approach, the present study provides a new strategy for preparing chirally Helical Polymer particles by making full use of achiral monomers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1679–1685

  • fabrication of optically active microparticles constructed by Helical Polymer quinine and their application to asymmetric michael addition
    Polymer, 2015
    Co-Authors: Haiyang Zhang, Wantai Yang, Jianping Deng
    Abstract:

    Abstract This article reports a novel category of optically active Polymer microparticles combining Helical substituted polyacetylene and quinine moieties. The microparticles were prepared through click reaction in aqueous system with the aid of stabilizer. The Polymer chains constituting the microparticles adopted Helical conformations of predominantly one-handed screw sense, according to circular dichroism and UV–vis spectroscopy measurements. The quinine pendants were grafted on the Helical Polymer chains and afforded the microparticles with catalytic ability for heterogeneous asymmetric Michael addition, in which a high product yield up to 86% and satisfactory enantioselectivity (83% ee) were obtained. An intriguing synergistic effect occurred in the asymmetric catalysis between the Helical macromolecular frameworks and pendent quinine moieties. The reusability of the microparticles was further demonstrated. The present study not only provides a new strategy for manufacturing Helical Polymer-immobilized chiral catalysts, but also opens up opportunities for developing novel macromolecular catalysts and even advanced functional chiral materials.

  • helix sense selective Polymerization of achiral substituted acetylene in chiral micelles for preparing optically active Polymer nanoparticles effects of chiral emulsifiers
    Polymer, 2014
    Co-Authors: Yan Li, Jianping Deng, Wantai Yang
    Abstract:

    Abstract This paper reports helix-sense-selective Polymerizations (HSSPs) of achiral acetylene monomer performed in chiral micelles, by which optically active Helical Polymer emulsions were directly obtained. The chiral micelles were constructed by chiral emulsifiers, in which achiral acetylene underwent HSSPs in the presence of catalyst [(nbd)RhCl] 2 . The chiral emulsifiers possessed different alkyl chain lengths and different amino acid groups, and their effects on HSSPs were investigated in detail. The obtained Polymer emulsions were characterized by TEM, circular dichroism and UV–vis absorption spectroscopy techniques. It is demonstrated that the Polymer chains constructing the emulsions adopted Helical structures of predominantly one-handed screw sense, from which the emulsions exhibited remarkable optical activity.

  • chiral Polymeric microspheres grafted with optically active Helical Polymer chains a new class of materials for chiral recognition and chirally controlled release
    Polymer Chemistry, 2013
    Co-Authors: Ci Song, Wantai Yang, Chaohong Zhang, Fangjie Wang, Jianping Deng
    Abstract:

    A new class of chiral microspheres (μm in size) was prepared via suspension Polymerization. The microspheres were constituted by optically active Helical substituted polyacetylenes, which render the microspheres with considerable optical activity according to CD and UV-vis spectroscopy measurements. The chiral microspheres exhibited large oil-absorbency (ca. 70 g g−1 toward CHCl3). The presence of Helical Polymer chains enabled the microspheres to show remarkable chiral recognition and chiral adsorption ability: the maximum adsorption toward D- and L-menthol was 90 and 25 wt%, respectively. More interestingly, the microspheres also demonstrated remarkable chirally controlled release ability: under similar conditions, the release of L- and D-menthol was 95 and 65 wt%, respectively. The present chiral microspheres open new possibilities for developing materials used for enantiomeric drug release.

  • optically active thermosensitive amphiphilic Polymer brushes based on Helical polyacetylene preparation through click onto grafting method and self assembly
    Polymer Bulletin, 2012
    Co-Authors: Lei Ding, Jianping Deng, Chunni Chen, Wantai Yang
    Abstract:

    Optically active, thermosensitive, and amphiphilic Polymer brushes, which consist of Helical poly(N-propargylamide) main chains and thermosensitive poly(N-isopropylacrylamide) (PNIPAm) side chains, were prepared via a novel methodology combining catalytic Polymerization, atom transfer radical Polymerization (ATRP), and click chemistry. Helical poly(N-propargylamide) bearing α-bromoisobutyryl pendent groups was synthesized via catalytic Polymerization, followed by substituting the –Br moieties with azido groups. Then, alkynyl terminated PNIPAm formed via ATRP was successfully grafted onto the azido functionalized Helical Polymer backbones via click chemistry, providing the expected Polymer brushes. GPC, FT-IR, and 1H-NMR measurements indicated the successful synthesis of the novel amphiphilic Polymer brushes. UV–vis and CD spectra evidently demonstrated the Helical structures of the Polymer backbones and the considerable optical activity of the final brushes. The Polymer brushes self-assembled in aqueous solution forming core/shell structured nanoparticles, which were comprised of optically active cores (Helical polyacetylenes) and thermosensitive shells (PNIPAm).

Biao Zhao - One of the best experts on this subject based on the ideXlab platform.

  • seed surface grafting precipitation Polymerization for preparing microsized optically active Helical Polymer core shell particles and their application in enantioselective crystallization
    Macromolecular Rapid Communications, 2018
    Co-Authors: Biao Zhao, Jianping Deng
    Abstract:

    : Core/shell particles constructed by Polymer shell and silica core have constituted a significant category of advanced functional materials. However, constructing microsized optically active Helical Polymer core/shell particles still remains as a big academic challenge due to the lack of effective and universal preparation methods. In this study, a seed-surface grafting precipitation Polymerization (SSGPP) strategy is developed for preparing microsized core/shell particles with SiO2 as core on which Helically substituted polyacetylene is covalently bonded as shell. The resulting core/shell particles exhibit fascinating optical activity and efficiently induce enantioselective crystallization of racemic threonine. Taking advantage of the preparation strategy, novel achiral Polymeric and hybrid core/shell particles are also expected.

  • intense circularly polarized luminescence contributed by Helical chirality of monosubstituted polyacetylenes
    Macromolecules, 2018
    Co-Authors: Biao Zhao, Kai Pan, Jianping Deng
    Abstract:

    Introducing fluorescent chromophores to Helical architectures can generate circularly polarized luminescence (CPL). Herein, a series of fluorescent chiral Helical monosubstituted polyacetylenes showing both intense optical activity and CPL are prepared by coPolymerizing achiral fluorescent acetylenic monomer and a chiral monomer. The luminescence dissymmetry factor (glum) values of the obtained coPolymers can reach up to +0.136 and −0.264. The formation of predominantly one-handed Helical structures in the coPolymer backbones has proved to play crucial roles in achieving the intense CPL. The dynamic Helical Polymer chains further enable the CPL-active materials to exhibit both solvent sensitivity and temperature sensitivity. Moreover, the Helical Polymer structures can also helpfully restrain the aggregation-caused quenching (ACQ) effect of fluorescent groups. Therefore, the Helical Polymers play double roles: providing Helical chirality for generating CPL and simultaneously circumventing ACQ effect of ch...

  • Intense Circularly Polarized Luminescence Contributed by Helical Chirality of Monosubstituted Polyacetylenes
    2018
    Co-Authors: Biao Zhao, Kai Pan, Jianping Deng
    Abstract:

    Introducing fluorescent chromophores to Helical architectures can generate circularly polarized luminescence (CPL). Herein, a series of fluorescent chiral Helical monosubstituted polyacetylenes showing both intense optical activity and CPL are prepared by coPolymerizing achiral fluorescent acetylenic monomer and a chiral monomer. The luminescence dissymmetry factor (glum) values of the obtained coPolymers can reach up to +0.136 and −0.264. The formation of predominantly one-handed Helical structures in the coPolymer backbones has proved to play crucial roles in achieving the intense CPL. The dynamic Helical Polymer chains further enable the CPL-active materials to exhibit both solvent sensitivity and temperature sensitivity. Moreover, the Helical Polymer structures can also helpfully restrain the aggregation-caused quenching (ACQ) effect of fluorescent groups. Therefore, the Helical Polymers play double roles: providing Helical chirality for generating CPL and simultaneously circumventing ACQ effect of chromophores. The present study provides new insights into designing and preparing advanced functional chiroptical materials

  • Combining Chiral Helical Polymer with Achiral Luminophores for Generating Full-Color, On–Off, and Switchable Circularly Polarized Luminescence
    2018
    Co-Authors: Biao Zhao, Kai Pan, Jianping Deng
    Abstract:

    Circularly polarized luminescent (CPL) materials are currently drawing ever-increasing interest. This contribution reports the first success in simply combining chiral Helical substituted polyacetylenes (HSPAs) with achiral luminophores to fabricate CPL materials demonstrating a high dissymmetry factor (glum) up to 10–1, despite neither covalent nor noncovalent interactions occurring between the two components. Circularly polarized scattering and fluorescence-selective absorption mechanisms are proposed for the generation of CPL, and a “matching rule” is further established for selecting chiral Polymers and achiral luminophores for the purpose. Taking advantage of the circularly polarized scattering effect, full-color tunable CPL materials are prepared from the combination of achiral fluorescent dyes and chiral HSPAs. Following the fluorescence-selective absorption mechanism, functional composite films with on–off and switchable CPL performance are fabricated. Also, remarkably, the glum value in the prepared materials can reach up to +0.323. The present study provides a simple, powerful, and universal strategy for constructing novel CPL materials

  • emulsion Polymerization of acetylenics for constructing optically active Helical Polymer nanoparticles
    Polymer Reviews, 2017
    Co-Authors: Biao Zhao, Jianping Deng
    Abstract:

    ABSTRACTEmulsion Polymerizations of acetylenics have largely advanced in recent years for preparing Polymer nanoparticles and emulsions thereof. This article presents a review on polyacetylene-derived nanoparticles with emphasis on the preparation of optically active Helical Polymer particles through emulsion Polymerization processes. Chiral Polymer nanoparticles obtained by emulsion Polymerization techniques are classified into four main groups: nanoparticles, core/shell nanoparticles, hollow particles, and hybrid materials consisting of nanoparticles of the kind. Helix-sense-selective emulsion Polymerizations are equally highlighted. Perspectives on the novel chiral Polymer particles are also provided. This review article is expected to inspire more interest in advanced chiral Polymeric nanoparticles.

Jinrui Deng - One of the best experts on this subject based on the ideXlab platform.

  • optically active microspheres from Helical substituted polyacetylene with pendent ferrocenyl amino acid derivative preparation and recycling use for direct asymmetric aldol reaction in water
    Polymer, 2017
    Co-Authors: Jinrui Deng, Jianping Deng
    Abstract:

    Abstract The contribution reports a novel type of chiral microspheres in which ferrocenyl amino-acid derived catalytic moieties were integrated with optically active Helical substituted polyacetylene. The microspheres were prepared by suspension coPolymerization of achirally and chirally substituted acetylenic monomers in a quantitative yield. SEM images showed the microspheres' regular spherical morphology. Circular dichroism and UV−vis absorption spectra demonstrated that the coPolymer chains constituting the microspheres adopted predominantly one-handed helices, endowing the microspheres with optical activity. The microspheres were further used to catalyze aldol reaction between cyclohexanone and p -nitrobenzaldehyde in water media in the presence of Brosted acid, providing the product with remarkable yield (up to 91%) and enantiomeric excess (up to 93%). Synergistic effects occurred in the Helical Polymer chains and the pendant catalytic moieties. The catalytic microspheres can be finely recycled and reused three times without significant loss of catalytic ability and enantio-selectivity.

  • optically active Helical polyacetylene bearing ferrocenyl amino acid derivative in pendants preparation and application as chiral organocatalyst for asymmetric aldol reaction
    Industrial & Engineering Chemistry Research, 2016
    Co-Authors: Jinrui Deng, Biao Zhao, Jianping Deng
    Abstract:

    The article reports a novel type of Helical Polymer-based chiral catalyst for catalyzing asymmetric aldol reactions. Chiral acetylenic monomers containing ferrocenyl amino-acid derivative substituent were synthesized for the first time and structurally identified. The investigated amino acids include alanine and threonine enantiomers. The obtained monomers separately underwent solution homoPolymerization and coPolymerization with an achirally substituted acetylene monomer in the presence of [Rh(nbd)Cl]2 and Et3N. Circular dichroism and UV–vis absorption spectra demonstrated that the coPolymer chains adopted predominantly one-handed helices, endowing the coPolymers with optical activity. The resulting (co)Polymers were further used to catalyze aldol reaction between cyclohexanone and p-nitrobenzaldehyde. Only threonine-derived coPolymers efficiently catalyzed the aldol reaction. A remarkable yield (up to 90%) and enantiomeric excess (up to 93%) were obtained. A synergic effect between the Helical structure...

  • emulsification induced homohelicity in racemic Helical Polymer for preparing optically active Helical Polymer nanoparticles
    Macromolecular Rapid Communications, 2016
    Co-Authors: Biao Zhao, Jinrui Deng, Jianping Deng
    Abstract:

    : Optically active nano- and microparticles have constituted a significant category of advanced functional materials. However, constructing optically active particles derived from synthetic Helical Polymers still remains as a big challenge. In the present study, it is attempted to induce a racemic Helical Polymer (containing right- and left-handed helices in equal amount) to prefer one predominant helicity in aqueous media by using emulsifier in the presence of chiral additive (emulsification process). Excitingly, the emulsification process promotes the racemic Helical Polymer to unify the helicity and directly provides optically active nanoparticles constructed by chirally Helical Polymer. A possible mechanism is proposed to explain the emulsification-induced homohelicity effect. The present study establishes a novel strategy for preparing chirally Helical Polymer-derived optically active nanoparticles based on racemic Helical Polymers.

  • Optically Active Helical Polyacetylene Self-Assembled into Chiral Micelles Used As Nanoreactor for Helix-Sense-Selective Polymerization
    2016
    Co-Authors: Biao Zhao, Jinrui Deng, Jianping Deng
    Abstract:

    Chiral micelles have been drawing ever-increasing attention because of their potentials in mimicking the unique stereochemical effects of enzymes. This article reports on the first success in preparing chiral micelles through self-assembly of Helical polyacetylene bearing cholic acid pendants. The micelles were further used as chiral nanoreactor, in which achiral acetylenic monomer smoothly underwent helix-sense-selective Polymerization (HSSP). The HSSPs directly established optically active core/shell nanoparticles whose shell and core both were constructed by Helical Polymers. The shells (or micelles) provided a protective effect for the preferably induced one-handed Helical Polymer chains in the cores. The present work provides insights into the self-assembly of chiral Helical Polymers, and also provides a powerful strategy for constructing novel chiral Polymer nanoarchitectures

  • Optically Active Helical Polyacetylene Bearing Ferrocenyl Amino-Acid Derivative in Pendants. Preparation and Application as Chiral Organocatalyst for Asymmetric Aldol Reaction
    2016
    Co-Authors: Jinrui Deng, Biao Zhao, Jianping Deng
    Abstract:

    The article reports a novel type of Helical Polymer-based chiral catalyst for catalyzing asymmetric aldol reactions. Chiral acetylenic monomers containing ferrocenyl amino-acid derivative substituent were synthesized for the first time and structurally identified. The investigated amino acids include alanine and threonine enantiomers. The obtained monomers separately underwent solution homoPolymerization and coPolymerization with an achirally substituted acetylene monomer in the presence of [Rh­(nbd)­Cl]2 and Et3N. Circular dichroism and UV–vis absorption spectra demonstrated that the coPolymer chains adopted predominantly one-handed helices, endowing the coPolymers with optical activity. The resulting (co)­Polymers were further used to catalyze aldol reaction between cyclohexanone and p-nitrobenzaldehyde. Only threonine-derived coPolymers efficiently catalyzed the aldol reaction. A remarkable yield (up to 90%) and enantiomeric excess (up to 93%) were obtained. A synergic effect between the Helical structures in the coPolymer main chains and the pendent catalytic moieties was found to play a crucial role in the asymmetric catalysis

Eiji Yashima - One of the best experts on this subject based on the ideXlab platform.

  • chiral amplification in double stranded Helical Polymers through chiral and achiral amidinium carboxylate salt bridges
    Polymer Journal, 2012
    Co-Authors: Wataru Makiguchi, Yoshio Furusho, Shinzo Kobayashi, Eiji Yashima
    Abstract:

    A series of m-terphenyl-based random coPolymers of chiral and achiral amidines, and their complementary homoPolymers of achiral carboxylic acids were prepared by the coPolymerization of a p-diiodobenzene derivative, with the diethynyl monomers containing a chiral or achiral amidine group and a carboxyl group using the Sonogashira coupling reaction. The obtained chiral/achiral amidine coPolymers assembled into a double-stranded Helical structure upon complexation with the complementary achiral homoPolymer of carboxylic acids through interstrand amidinium−carboxylate salt bridges. The complexes exhibited characteristic induced cotton effects in the π-conjugated main-chain chromophore regions, indicating that the interstrand duplexes possess a preferred-handed double-Helical structure. The effect of the chiral and achiral amidine contents on the amplification of the Helical chirality (‘the sergeants and soldiers effect’) during the interstrand double-helix formation was investigated by comparing the cotton effect patterns and intensities of the duplexes with those of the corresponding all-chiral amidine-based double-Helical Polymer. m-Terphenyl-based random coPolymers of chiral and achiral amidines and its complementary homoPolymer of achiral carboxylic acids self-assembled to form complementary double helices with a preferred-handed Helical sense via interstrand amidinium–carboxylate salt bridges, thus showing induced cotton effects in the π-conjugated main-chain chromophore regions. A unique amplification of the Helical chirality (‘the sergeants and soldiers effect’) was, for the first time, observed during the double-helix formation.

  • separation of c70 over c60 and selective extraction and resolution of higher fullerenes by syndiotactic Helical poly methyl methacrylate
    Journal of the American Chemical Society, 2010
    Co-Authors: Takehiro Kawauchi, Jiro Kumaki, Atsushi Kitaura, Mariko Kawauchi, Tsutomu Takeichi, Hiroki Iida, Eiji Yashima
    Abstract:

    A one-handed Helical Polymer, syndiotactic poly(methyl methacrylate) (st-PMMA), recognizes the size and chirality of higher fullerenes through an induced-fit mechanism and can selectively extract enantiomers of the higher fullerenes, such as C76, C80, C84, C86, C88, C90, C92, C94, and C96. This discovery will generate a practical and valuable method for selectively extracting the elusive higher fullerenes and their enantiomers and opens the way to developing novel carbon cage materials with optical activities.

  • two dimensional surface chirality control by solvent induced helicity inversion of a Helical polyacetylene on graphite
    Journal of the American Chemical Society, 2006
    Co-Authors: Shinichiro Sakurai, Kento Okoshi, Jiro Kumaki, Eiji Yashima
    Abstract:

    We report the direct evidence for the macromolecular helicity inversion of a Helical poly(phenylacetylene) bearing l- or d-alanine pendants with a long alkyl chain in different solvents by atomic force microscopy observations of the diastereomeric Helical structures. The diastereomeric Helical poly(phenylacetylene)s induced in polar and nonpolar solvents self-assembled into ordered, two-dimensional helix bundles with controlled molecular packing, Helical pitch, and handedness on graphite upon exposure of each solvent. The macromolecular helicity deposited on graphite from a polar solvent further inverted to the opposite handedness by exposure to a specific nonpolar solvent, and these changes in the surface chirality based on the inversion of helicity could be visualized by atomic force microscopy with molecular resolution, and the results were quantified by X-ray diffraction of the oriented liquid crystalline, diastereomeric Helical Polymer films.

  • helix sense controlled Polymerization of a single phenyl isocyanide enantiomer leading to diastereomeric Helical polyisocyanides with opposite helix sense and cholesteric liquid crystals with opposite twist sense
    Journal of the American Chemical Society, 2006
    Co-Authors: Takashi Kajitani, Kento Okoshi, Shinichiro Sakurai, Jiro Kumaki, Eiji Yashima
    Abstract:

    We report the unprecedented helix-sense controlled Polymerization of enantiomerically pure phenyl isocyanides bearing an l- or d-alanine pendant with a long alkyl chain. The Polymerization with an achiral nickel catalyst diastereoselectively proceeds, resulting in either a right- or left-handed Helical Polymer, whose helix-sense can be controlled by the Polymerization solvent and temperature. Both the diastereomeric right- and left-handed Helical Polymers further self-assemble into lyotropic cholesteric liquid crystals with opposite twist-senses. Consequently, the macromolecular helicity and mesoscopic, supramolecular cholesteric twist can be controlled by the molecular chirality of the pendant of a single enantiomeric phenyl isocyanide through the Polymerization under either kinetic or thermodynamic control assisted by hydrogen bonds. High-resolution atomic force microscopy revealed their Helical conformations and enabled the determination of the Helical sense.