Visualized thermoresponsive helix-helix switch of polyphenylacetylene with a wide-range tunable transition temperature  

作　　者：Sheng Wang Siyu Xie Hongxu Du Hua Zeng Jie Zhang Xinhua Wan 

机构地区：[1]Beijing National Laboratory for Molecular Sciences,Key Laboratory of Polymer Chemistry and Physics of Ministry of Education,College of Chemistry and Molecular Engineering,Peking University,Beijing 100871,China

出　　处：《Science China Chemistry》2023年第3期887-895,共9页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China(51833001,51921002,52103001);the China Postdoctoral Science Foundation(2021T140007,2020M680191).

摘　　要：Polymers with tunable helicity and naked-eye structural change under external stimuli are valuable for fabricating smart materials. Herein, we report a novel thermoresponsive color and fluorescent polyphenylacetylene switch with a tunable critical temperature. It relies on the temperature and solvent sensitivity of intramolecular n→π* interactions between the vicinal carbonyl groups of ester substituents located at 3,5-positions, which are indispensable for forming the cis-cisoid helical conformation of polyene backbones. In a properly chosen solvent, a compressed cis-cisoid helix is stabilized by n→π* interactions at low temperatures and yields a colorless solution. Increasing temperature causes the conformational transition toward an extended cis-transoid helix due to the disruption of n→π* interactions and produces a yellow solution. Reducing the hydrogen bond donating ability or polarity of solvents increases the switching temperature. By introducing a fluorogenic pendant, this conformational transition can also be read out by fluorescence quenching. This work may open a new window for developing intelligent materials through precisely tuning conformational transitions.

关 键 词：POLYPHENYLACETYLENE THERMORESPONSIVE conformation transition fluorescent switch n→π*interaction 

分 类 号：O657.3[理学—分析化学]