Helix-Sense-Controlled Synthesis of Optically Active Poly(methyl methacrylate) Stereocomplexes

Kawauchi, Takehiro; Kitaura, Atsushi; Kumaki, Jiro; Kusanagi, Hiroshi; Yashima, Eiji

doi:10.1021/ja8048805

Cited by 89 publications

(85 citation statements)

References 19 publications

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“…As a consequence, the stereocomplex may not be an intertwined double helix, but may be a supramolecular-assembled inclusion complex composed of an outer st-PMMA helix and an inner it-PMMA double helix. This speculation is supported by the fact that st-PMMA can encapsulate fullerenes and it-PMMA within its helical cavity to form robust and peapod-like inclusion complexes 80 and a stereocomplex, 98 respectively. Recently, we found that a preferred-handed helical st-PMMA can be induced in toluene in the presence of optically active alcohols, such as (S)-or (R)-2-phenylethanol (38), resulting in an optically active gel, which showed a VCD in PMMA infrared regions.…”

Section: Synthesis and Structures Of Helical Polymers E Yashimamentioning

confidence: 99%

“…Interestingly, the induced helical structure of the st-PMMA/fullerene complex can be memorized after complete removal of chiral alcohols and the complex exhibited a similar VCD because of the original PMMA in infrared regions, as well as an induced CD in the encapsulated C 60 chromophore regions, although C 60 itself is achiral. 80 Taking advantage of the helicity induction and memory effect in st-PMMA and its inclusion complexation ability, an optically active stereocomplex with a supramolecular helicity memory has been prepared through the inclusion of it-PMMA double helix within the helical cavity of an optically active st-PMMA (Figure 14), 98 Figure 12 Structure of a complementary double-stranded helical polymer (37). (a) Atomic force microscopy (AFM) phase image of two-dimensional self-assembled 37 on highly oriented pyrolytic graphite with the height profile measured along the dashed line in the image and (b) high-resolution AFM image of 37.…”

Section: Synthesis and Structures Of Helical Polymers E Yashimamentioning

confidence: 99%

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Synthesis and structure determination of helical polymers

Yashima

2010

Polym J

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During the last decade, remarkable progress in developing synthetic helical polymers with a controlled helical sense has been achieved. However, the exact helical structures of most of the already prepared synthetic helical polymers remain unsolved. In this review, the recent progress in the synthesis of helical polymers and their structural determination, including helical pitch and handedness based on X-ray diffraction and spectroscopic measurements, together with high-resolution atomic force microscopy, is described. Polymer Journal (2010) 42, 3-16; doi:10.1038/pj.2009 Keywords: atomic force microscopy; circular dichroism; helical polymer; helical structure; X-ray diffractionThe helix is a unique structure as observed in nature from microscopic to macroscopic levels and is inherently chiral. Inspired by biological helices, such as DNA and proteins, chemists have been challenged to synthesize helical polymers with a controlled helical sense that aims not only to mimic biological helical structures but also to develop chiral materials for the separation of enantiomers and asymmetric catalysis. [1][2][3][4][5][6][7][8][9][10][11][12] The history of synthetic helical polymers with optical activity extends back to the 1960s when Pino and Lorenzi 13 investigated the structural and chiroptical properties of isotactic vinyl polymers prepared by the polymerization of a-olefins bearing optically active substituents. Although helical polyolefins are totally dynamic in nature and consist of short helical segments separated by frequently occurring helical reversals among disordered, random coil conformations, 14 this study was significant in the field of synthetic helical polymers, from which a number of helical polymers have been synthesized.On the basis of the pioneering studies by Nolte et al., 15 Okamoto et al. 16 and Green et al., 17 the existing synthetic helical polymers that exhibit an optical activity solely because of their macromolecular helicity can be classified into two categories with respect to their helix inversion barriers, that is, static and dynamic helical polymers (Figure 1). 9,12 Optically active helical polymers, such as poly(triphenylmethyl methacrylate) (1), 16 poly(t-butyl isocyanide) (2) 15 and polychloral (3), 18 have a sufficiently high helix inversion barrier and belong to the family of static helical polymers. Therefore, these helical polymers with either a right-or left-handed helix can be prepared by the helix-sense-selective polymerization of the corresponding achiral monomers using chiral catalysts or initiators under kinetic control. On the other hand, dynamic helical polymers, such as polyisocyanates (8) 17 and polysilanes (9), 19 possess a very low helix inversion barrier.As a consequence, they consist of interconvertible right-and lefthanded helical segments separated by rarely occurring helical reversals, as demonstrated by Green et al.,6,20,21 so that a preferred-handed helical conformation can be induced in the presence of a small amount of chiral residues at the pendant 6 or ter...

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Section: Synthesis and Structures Of Helical Polymers E Yashimamentioning

confidence: 99%

Section: Synthesis and Structures Of Helical Polymers E Yashimamentioning

confidence: 99%

Synthesis and structure determination of helical polymers

Yashima

2010

Polym J

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“…We also found that a preferred‐handed helical st‐PMMA can serve as an optically active polymeric host to encapsulate the complementary isotactic PMMA (it‐PMMA) in a helix‐sense‐controlled manner to produce the first optically active PMMA stereocomplex 6b, 10…”

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“…Herein we report a novel strategy to construct a unique “helix‐in‐helix”3a,3b, 5, 6b, 12 supramolecular structure composed of C 60 ‐bound one‐handed 3 10 ‐helical13 peptides (fulleropeptides)14 ( l ‐ 1 and d ‐ 1 ) wrapped by a helical st‐PMMA (Figure 1 a), and at the same time, a preferred‐handed helical structure is induced in the st‐PMMA backbone during the inclusion complex formation. …”

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“Helix‐in‐Helix” Superstructure Formation through Encapsulation of Fullerene‐Bound Helical Peptides within a Helical Poly(methyl methacrylate) Cavity

et al. 2016

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A one‐handed 310‐helical hexapeptide is efficiently encapsulated within the helical cavity of st‐PMMA when a fullerene (C60) derivative is introduced at the C‐terminal end of the peptide. The encapsulation is accompanied by induction of a preferred‐handed helical conformation in the st‐PMMA backbone with the same‐handedness as that of the hexapeptide to form a crystalline st‐PMMA/peptide‐C60 inclusion complex with a unique optically active helix‐in‐helix structure. Although the st‐PMMA is unable to encapsulate the 310‐helical peptide without the terminal C60 unit, the helical hollow space of the st‐PMMA is almost filled by the C60‐bound peptides. This result suggests that the C60 moiety can serve as a versatile molecular carrier of specific molecules and polymers in the helical cavity of the st‐PMMA for the formation of an inclusion complex, thus producing unique supramolecular soft materials that cannot be prepared by other methods.

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“…11 The st-PMMA gel and its inclusion complex with C 60 were prepared according to previously reported methods with a slight modification. 3,5,12 St-PMMA (4 mg) was dissolved in toluene (0.1 mL) containing 112 (2 equiv with respect to the monomer units of st-PMMA) upon heating at 110°C. Cooling to room temperature, the gelation rapidly took place within 4 min except for the solutions with 1 (3 h) and 3 (10 min) (Table S1).…”

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Helicity Induction and Memory of Syndiotactic Poly(methyl methacrylate) Assisted by Optically Active Additives and Solvents and Chiral Amplification of Helicity

Kitaura¹,

Iida²,

Kawauchi

et al. 2010

Chemistry Letters

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Syndiotactic poly(methyl methacrylate) (st-PMMA) was found to fold into a preferred-handed helix with amplification of helicity assisted by chiral additives and solvents and further encapsulated fullerenes within its helical cavity whose helicity was memorized after removal of the chiral molecules.Syndiotactic poly(methyl methacrylate) (st-PMMA), a stereoregular commodity polymer, forms a thermoreversible gel in aromatic solvents, such as toluene and chlorobenzene, in which the st-PMMA possesses a 74/4 helical conformation with a large cavity of about 1 nm and the solvent molecules are encapsulated in the cavity of the st-PMMA interior.

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Helix-Sense-Controlled Synthesis of Optically Active Poly(methyl methacrylate) Stereocomplexes

Cited by 89 publications

References 19 publications

Synthesis and structure determination of helical polymers

Synthesis and structure determination of helical polymers

“Helix‐in‐Helix” Superstructure Formation through Encapsulation of Fullerene‐Bound Helical Peptides within a Helical Poly(methyl methacrylate) Cavity

Helicity Induction and Memory of Syndiotactic Poly(methyl methacrylate) Assisted by Optically Active Additives and Solvents and Chiral Amplification of Helicity

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