A structural study on chiral poly(methacrylic acid) polymerized with chitosan templates

•Helical poly(methacrylic acid) (PMAA) was synthesized under the presence of chitosan templates.•The molecular structure was analyzed by means of NMR, IR/Raman, X-ray diffraction, CD spectra, and DFT calculations.•The tacticity was proved to be syndiotactic with (TTGG)2 conformation, forming left-ha...

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Veröffentlicht in:Journal of molecular structure 2024-01, Vol.1295, p.136710, Article 136710
Hauptverfasser: Sayama, Daisuke, Hatanaka, Masashi, Miyasaka, Makoto
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Sprache:eng
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Zusammenfassung:•Helical poly(methacrylic acid) (PMAA) was synthesized under the presence of chitosan templates.•The molecular structure was analyzed by means of NMR, IR/Raman, X-ray diffraction, CD spectra, and DFT calculations.•The tacticity was proved to be syndiotactic with (TTGG)2 conformation, forming left-handed helical sense.•The 21-helicity induced by the single strand of chitosans leads to an orthorhombic lattice with the P2221 space group.•The chirality formally followed the helical rule for C2 molecules. Poly(methacrylic acid) (PMAA) with a two-fold helical axis was synthesized from sodium methacrylate in the presence of chitosans. The polymer chain formed a two-fold helix with a syndiotactic conformation, in which the sequence of the bond rotation was (TTGG)2 (T- trans, G- gauche). The PMAA was optically active to produce a negative Cotton effect in the UV region. The crystalline powder of PMAA was found to form an orthorhombic lattice with a = 7.94, b = 6.51, and c = 7.99 Å (identical period), of which the space group was determined to be P2221. The astonishing crystallinity of this compound comes from template polymerization with a chiral strand of chitosan. Electronic structures of stereoregular PMAA isomers are also discussed from the perspective of band theory and spectroscopic data. The helical sense was determined to be left-handed by circular dichroism and quantum-chemical calculations, which followed the helical rule for C2 molecules. [Display omitted]
ISSN:0022-2860
1872-8014
DOI:10.1016/j.molstruc.2023.136710