Two modes of asymmetric polymerization of phenylacetylenes having an L‐amino alcohol residue and two hydroxy groups |
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| Authors: | Hongge Jia Jun Li Yu Zang Toshiki Aoki Masahiro Teraguchi Takashi Kaneko |
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| Institution: | 1. Department of Polymeric Material and Engineering, Qiqihar University, Wenhua Street 42, Qiqihar 161006, China;2. Department of Chemistry and Chemical Engineering, Graduate School of Science and Technology, Niigata University, Ikarashi 2‐8050, Nishi‐Ku, Niigata 950‐2181, Japan;3. Center for Education and Research on Environmental Technology, Materials Engineering, Nanochemistry, Niigata University, Ikarashi 2‐8050, Nishi‐Ku, Niigata 950‐2181, Japan;4. Center for Transdisciplinary Research, Niigata University, Ikarashi 2‐8050, Nishi‐Ku, Niigata 950‐2181, Japan |
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| Abstract: | Four novel chiral phenylacetylenes having an L ‐amino alcohol residue and two hydroxymethyl groups were synthesized and polymerized by an achiral catalyst ((nbd)Rh+η6‐(C6H5)B?(C6H5)3]) or a chiral catalytic system (Rh(nbd)Cl]2/(S)‐ or (R)‐phenylethylamine ((S)‐ or (R)‐PEA)). The two resulting polymers having an L ‐valinol or L ‐phenylalaninol residue showed Cotton effects at wavelengths around 430 nm. This observation indicated that they had an excess of one‐handed helical backbones. Positive and negative Cotton effects were observed only for the polymers having an L ‐valinol residue produced by using (R)‐ and (S)‐PEA as a cocatalyst, respectively, although the monomer had the same chirality. Even when the achiral catalyst was used, the two resulting polymers having an L ‐valinol or L ‐phenylalaninol residue showed Cotton effects despite the long distance between the chiral groups and the main chain. We have found the first example of a new type of chiral monomer, that is, a chiral phenylacetylene monomer having an L ‐amino alcohol residue and two hydroxy groups that was suitable for both modes of asymmetric polymerization, that is, the helix‐sense‐selective polymerization ( HSSP ) with the chiral catalytic system and the asymmetric‐induced polymerization ( AIP ) with the achiral catalyst. The other two monomers having L ‐alaninol and L ‐tyrosinol were found to be unsuitable to neither HSSP nor AIP because of their polymers' low solubility. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 |
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| Keywords: | asymmetric polymerization catalysts chiral conjugated polymers initiators L‐amino alcohol polyacetylenes |
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