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Control of Intramolecular Hydrogen Bonding in a Conformation‐Switchable Helical‐Spring Polymer by Solvent and Temperature
Author(s) -
Jin YoungJae,
Aoki Toshiki,
Kwak Giseop
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201910269
Subject(s) - intramolecular force , hydrogen bond , phenylacetylene , polymer , solvent , chemistry , crystallography , helix (gastropod) , photochemistry , molecule , stereochemistry , organic chemistry , ecology , snail , biology , catalysis
A substituted poly(phenylacetylene) derivative (PPA HB ) with two hydroxymethyl groups at the meta position of the side phenyl ring was examined as a conformation‐switchable helical spring polymer that responds to solvent and heat stimuli in a precisely controlled manner. Intramolecular hydrogen bonds, which cause the helical structure of the polymer, were broken and re‐formed by adjusting the hydrogen‐bonding strength values (p K HB ) of various combinations of solvents or by varying the temperature. In this process, a reversible conformational change from cis – cisoid to cis – transoid , accompanied by a phase transition in the form of a helix‐coil transformation occurred, with the polymer exhibiting critical changes of color fading and recovery in specific environments. These results demonstrate that PPA HB can be used as either a p K HB indicator or a thermometer. The color changes of the polymer solution are described in detail based on spectroscopic analyses and thermodynamic considerations.

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