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

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Science China Chemistry 2023年第3期66卷 887-895页

作者： Sheng Wang Siyu Xie Hongxu Du Hua Zeng Jie Zhang Xinhua Wan Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

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

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UV LASER INITIATED STEREOSELECTIVE HOMOGENEOUS CATALYSIS POLYMERIZATION OF PHENYLACETYLENE

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Chinese Journal of Polymer Science 1993年第3期11卷 236-241页

作者：张杰佘永柏傅克坚周以华 Institute of Physics Chinese Academy of Sciences Beijing 100080 National Center for Certified Reference Materials Beijing 100013

In this paper, the stereoselective homogeneous catalysis polymerization of phenylacetylene by using two kinds of catalysts W(CO)_5CH_3I and W(CO)_4I_2 produced from UV laser photolysis of W (CO)_6 in CH_3I, I_2—C_6H_6 and CHI_3—C_6H_6 respectively was studied. The effects of laser energy, laser irradiation time and lifetime of catalyst on the polymerization of phenylacetylene were discussed. The photoproducts of W (CO)_6 in CH_3I, I2—C_6H_6 and CHI_3—C_6I_6 were determined by IR spectra. The structures of polyphenylacetylene obtained by W (CO)_5CH_3I and W (CO)_4I_2 catalysts were characterized by IR spectra and ~1H NMR spectra.

关键词： UV laser initiation polyphenylacetylene Homogeneous catalysis polymerization.

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