Macromolecular helicity inversion of poly(phenylacetylene) derivatives induced by various external stimuli |
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Authors: | Katsuhiro Maeda Kazuhide Morino Eiji Yashima |
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Institution: | Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan |
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Abstract: | Unique macromolecular helicity inversion of stereoregular, optically active poly(phenylacetylene) derivatives induced by external achiral and chiral stimuli is briefly reviewed. Stereoregular, cis-transoidal poly(phenylacetylene)s bearing an optically active substituent, such as (1R,2S)-norephedrine (poly- 1 ) and β-cyclodextrin residues (poly- 2 ), show an induced circular dichroism (ICD) in the UV-visible region of the polymer backbone in solution due to a predominantly one-handed helical conformation of the polymers. However, poly- 1 undergoes a helix-helix transition upon complexation with chiral acids having an R configuration, and the complexes exhibit a dramatic change in the ICD of poly- 1 . Poly- 2 also shows the inversion of macromolecular helicity responding to molecular and chiral recognition events that occurred at the remote cyclodextrin residues from the polymer backbone; the helicity inversion is accompanied by a visible color change. A similar helix-helix transition of poly((R)- or (S)-(4-((1-(1-naphthyl)ethyl)carbamoyl)phenyl)acetylene) is also briefly described. |
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Keywords: | chiral helix helix-helix transition induced circular dichroism polyacetylenes |
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