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Molecules 2012, 17(1), 433-451; doi:10.3390/molecules17010433
Article

Synthesis of Stable and Soluble One-Handed Helical Homopoly(substituted acetylene)s without the Coexistence of Any Other Chiral Moieties via Two-Step Polymer Reactions in Membrane State: Molecular Design of the Starting Monomer

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Received: 15 December 2011; in revised form: 28 December 2011 / Accepted: 30 December 2011 / Published: 4 January 2012
(This article belongs to the Special Issue Chiroptical Techniques)
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Abstract: A soluble and stable one-handed helical poly(substituted phenylacetylene) without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer followed by two-step polymer reactions in membrane state: (1) removing the chiral groups (desubstitution); and (2) introduction of achiral long alkyl groups at the same position as the desubstitution to enhance the solubility of the resulting one-handed helical polymer (resubstitution). The starting chiral monomer should have four characteristic substituents: (i) a chiral group bonded to an easily hydrolyzed spacer group; (ii) two hydroxyl groups; (iii) a long rigid hydrophobic spacer between the chiral group and the polymerizing group; (iv) a long achiral group near the chiral group. As spacer group a carbonate ester was selected. The two hydroxyl groups formed intramolecular hydrogen bonds stabilizing a one-handed helical structure in solution before and after the two-step polymer reactions in membrane state. The rigid long hydrophobic spacer, a phenylethynylphenyl group, enhanced the solubility of the starting polymer, and realized effective chiral induction from the chiral side groups to the main chain in the asymmetric-induced polymerization. The long alkyl group near the chiral group avoided shrinkage of the membrane and kept the reactivity of resubstitution in membrane state after removing the chiral groups. The g value (g = ([θ]/3,300)/ε) for the CD signal assigned to the main chain in the obtained final polymer was almost the same as that of the starting polymer in spite of the absence of any other chiral moieties. Moreover, since the one-handed helical structure was maintained by the intramolecular hydrogen bonds in a solution, direct observation of the one-handed helicity of the final homopolymer has been realized in CD for the solution for the first time.
Keywords: one-handed helicity; chirality; polymer reaction; membrane; phenylacetylene; asymmetric polymerization; solubility one-handed helicity; chirality; polymer reaction; membrane; phenylacetylene; asymmetric polymerization; solubility
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Abe, Y.; Aoki, T.; Jia, H.; Hadano, S.; Namikoshi, T.; Kakihana, Y.; Liu, L.; Zang, Y.; Teraguchi, M.; Kaneko, T. Synthesis of Stable and Soluble One-Handed Helical Homopoly(substituted acetylene)s without the Coexistence of Any Other Chiral Moieties via Two-Step Polymer Reactions in Membrane State: Molecular Design of the Starting Monomer. Molecules 2012, 17, 433-451.

AMA Style

Abe Y, Aoki T, Jia H, Hadano S, Namikoshi T, Kakihana Y, Liu L, Zang Y, Teraguchi M, Kaneko T. Synthesis of Stable and Soluble One-Handed Helical Homopoly(substituted acetylene)s without the Coexistence of Any Other Chiral Moieties via Two-Step Polymer Reactions in Membrane State: Molecular Design of the Starting Monomer. Molecules. 2012; 17(1):433-451.

Chicago/Turabian Style

Abe, Yunosuke; Aoki, Toshiki; Jia, Hongge; Hadano, Shingo; Namikoshi, Takeshi; Kakihana, Yuriko; Liu, Lijia; Zang, Yu; Teraguchi, Masahiro; Kaneko, Takashi. 2012. "Synthesis of Stable and Soluble One-Handed Helical Homopoly(substituted acetylene)s without the Coexistence of Any Other Chiral Moieties via Two-Step Polymer Reactions in Membrane State: Molecular Design of the Starting Monomer." Molecules 17, no. 1: 433-451.



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