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Helix formation of poly(phenylacetylene) derivatives bearing amino groups at the meta position induced by optically active carboxylic acids
Authors:Katsuhiro Maeda  Seiji Okada  Eiji Yashima  Yoshio Okamoto
Abstract:Two novel phenylacetylene derivatives bearing diethylaminomethyl groups at the meta position on phenyl groups 3‐(N,N‐diethylaminomethyl)phenyl]acetylene ( 1 ) and 3,5‐bis(N,N‐diethylaminomethyl)phenyl]acetylene ( 2 ) were synthesized and polymerized with Rh(nbd)Cl]2 (nbd: norbornadiene). Both monomers gave highly cis–transoidal stereoregular polymers that exhibited an induced circular dichroism (ICD) in the UV–visible region, probably because of a prevailing one‐handed helical conformation upon complexation with optically active carboxylic acids such as mandelic acid and lactic acid. The sign of the Cotton effects reflected the absolute configuration of the chiral acids. Therefore, these polymers can be used as a novel probe for determining the configuration of chiral acids. The polymers were stable in the presence of chiral acids in solution. The poly‐ 1 complexed with chiral acids exhibited a split‐type ICD, whereas the poly‐ 2 complexed with chiral acids showed a different, non‐split‐type ICD. The ICD pattern of the poly‐ 1 /chiral acids complexes dramatically changed with an increase in the concentration of the chiral acids, thus showing a non‐split‐type ICD similar to those of the poly‐ 2 /chiral acid complexes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3180–3189, 2001
Keywords:poly(phenylacetylene)  cis‐transoid  helix  circular dichroism  induced circular dichroism  absolute configuration
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