화학공학소재연구정보센터
Journal of Polymer Science Part A: Polymer Chemistry, Vol.50, No.24, 5134-5143, 2012
Two modes of asymmetric polymerization of phenylacetylenes having an L-amino alcohol residue and two hydroxy groups
Four novel chiral phenylacetylenes having an L-amino alcohol residue and two hydroxymethyl groups were synthesized and polymerized by an achiral catalyst ((nbd)Rh+[?6-(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. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012