Eiji Yashima 교수

In this review, we describe the recent advances in supramolecular helical assemblies formed from chiral and achiral small molecules, oligomers (foldamers), and helical and nonhelical polymers from the viewpoints of their formations with unique chiral phenomena, such as amplification of chirality during the dynamic helically assembled processes, properties, and specific functionalities, some of which have not been observed in or achieved by biological systems. In addition, a brief historical over

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTHelical Polymers: Synthesis, Structures, and FunctionsEiji Yashima*†, Katsuhiro Maeda‡, Hiroki Iida†, Yoshio Furusho†, and Kanji Nagai†§View Author Information Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan, and Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan* E-mail: [email protected]†Nagoya University.‡K

A unique feature of synthetic helical polymers for the detection and amplification of chirality is briefly described in this article. In sharp contrast to host-guest and supramolecular systems that use small synthetic receptor molecules, chirality can be significantly amplified in a helical polymer, such as poly(phenylacetylene)s with functional pendants, which enable the detection of a tiny imbalance in biologically important chiral molecules through a noncovalent bonding interaction with high

Biological macromolecules, such as DNA and proteins, possess a unique and specific ordered structure, such as a right-handed double helix or a single alpha-helix. Those structures direct the sophisticated functions of these molecules in living systems. Inspired by biological helices, chemists have worked to synthesize polymers with controlled helicity, not only to mimic the biological helices but also to realize their functions. Although numerous synthetic polymers that fold into a single-handed

Unique macromolecules that fold into a preferred-handed helical conformation induced by external chiral stimuli are mainly described in this review. In contrast to small molecular systems, the chiral information of nonracemic guest molecules transfers with a significant amplification in a dynamic helical polymer, such as stereoregular poly(phenylacetylene)s bearing functional pendant groups as an excess of a single-handed helix through noncovalent bonding interaction, which provides an efficient

An optically inactive polyacetylene, poly((4-carboxyphenyl)acetylene) (poly-1), exhibits an induced circular dichroism (ICD) in the UV−visible region upon complexation with chiral amines and amino alcohols in DMSO and in the film, the sign of which reflects the stereochemistry including bulkiness, type (primary, secondary, or tertiary), and absolute configuration of the amines. Therefore, the polyacetylene can be used as a novel probe for determining the chirality of amines. Most primary amines

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPoly((4-carboxyphenyl)acetylene) as a Probe for Chirality Assignment of Amines by Circular DichroismEiji Yashima, Teruaki Matsushima, and Yoshio OkamotoCite this: J. Am. Chem. Soc. 1995, 117, 46, 11596–11597Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November 1995https://pubs.acs.org/doi/10.1021/ja00151a032https://doi.org/10.1021/ja00151a032research-articleACS PublicationsRequest reuse perm

Abstract Chromatographic enantioseparations, particularly resolution by high-performance liquid chromatography (HPLC), have advanced considerably in the past decade, and have become a practically useful method not only for determining their optical purity, but also for obtaining optical isomers. The preparation of a chiral stationary phase (CSP) capable of effective chiral recognition is the key to this separation technique. We have found that polysaccharide derivatives, particularly cellulose e

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSwitching of a Macromolecular Helicity for Visual Distinction of Molecular Recognition EventsEiji Yashima, Katsuhiro Maeda, and Osamu SatoView Author Information Department of Molecular Design and Engineering Graduate School of Engineering, Nagoya University Form and Function, PRESTO, JST, Chikusa-ku Nagoya 464-8603, Japan Cite this: J. Am. Chem. Soc. 2001, 123, 33, 8159–8160Publication Date (Web):July 28, 2001Publication History Received12 June

Chromatographic enantioseparation of 1,1‘-bi-2-naphthol (2) and its mono- and di-O-methylated derivatives (3a, 3b), 2,2‘-dihydroxy-6,6‘-dimethylbiphenyl (4), and 10,10‘-dihydroxy-9,9‘-biphenanthryl (5) has been performed on cellulose tris(5-fluoro-2-methylphenylcarbamate) (1) as a chiral stationary phase for high-performance liquid chromatography (HPLC). The complete base-line separation of 2 and 4 was achieved with the elution order of enantiomers such that the (R)-isomers eluted first followed

Cis-transoidal poly((4-carboxyphenyl)acetylene) (poly-1) is an optically inactive polymer but forms an induced one-handed helical structure upon complexation with optically active amines such as (R)-(1-(1-naphthyl)ethyl)amine ((R)-2) in DMSO. The complexes show a characteristic induced circular dichroism (ICD) in the UV-visible region of the polymer backbone. Moreover, the macromolecular helicity of poly-1 induced by (R)-2 can be "memorized" even after complete replacement of (R)-2 by various ac

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and Conformational Study of Optically Active Poly(phenylacetylene) Derivatives Bearing a Bulky SubstituentEiji Yashima, Songlin Huang, Teruyuki Matsushima, and Yoshio OkamotoCite this: Macromolecules 1995, 28, 12, 4184–4193Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue 1 June 1995https://pubs.acs.org/doi/10.1021/ma00116a020https://doi.org/10.1021/ma00116a020research-articleACS Publications

Direct observations of the helical structures of artificial helical polymers, such as helical polyacetylenes and polyisocyanides, by atomic force microscopy (AFM) are described in this tutorial review. The two-dimensional helix bundle formation of specific helical polymers on substrates under solvent vapor exposure permits us to determine their helical structures, including their helical pitch and handedness, at a molecular level by AFM in the tapping mode. The direct observation of supramolecul