Department of Chemistry, The Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Institute of Molecular Functional Materials, Division of Life Science and State Key Laboratory of Molecular Neuroscience , The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon , Hong Kong 999077.
HKUST-Shenzhen Research Institute , No.9 Yuexing first RD, South Area, Hi-tech Park, Nanshan, Shenzhen 518057 , China.
ACS Nano. 2020 Feb 25;14(2):2090-2098. doi: 10.1021/acsnano.9b08761. Epub 2020 Jan 10.
Molecules have limited mobility in the solid state because of the strong intermolecular interactions, and therefore, applications based on solid-state molecular motions are seldom explored. Herein, by manipulating the solid-state intramolecular motion of tetraphenylethylene (TPE) in a crystallizing polymer matrix, controlled fluorescent patterns with information storage and encoding functionality are developed. The intramolecular mobility of TPE can not only affect the fluorescence intensity but also determine the photocyclization activity, which can be tuned by surrounding polymer rigidity. The soft amorphous region in the semicrystalline polymer facilitates the intramolecular motion to achieve weak blue emission and high photocyclization activity, whereas the rigid crystalline phase restricts the intramolecular motion to give intense blue emission and low photoreactivity. Meanwhile, in the process of crystallization, the dynamic movement of the polymer chain in the crystal growth boundary layer further accelerates the intramolecular motions of TPE, allowing enhanced photoreactivity across crystalline and amorphous regions. The motion-dominated fluorescence allows TPE as a smart molecular robot to generate desired fluorescent patterns triggered by polymer crystallization. Our findings provide a correlation between microscopic molecular motions and macroscopic optical signals.
由于分子间的强相互作用，分子在固态中的迁移率有限，因此很少探索基于固态分子运动的应用。在此，通过操纵结晶聚合物基质中四苯乙烯（TPE）的固态分子内运动，开发了具有信息存储和编码功能的可控荧光图案。TPE 的分子内迁移率不仅会影响荧光强度，还会决定光环化活性，而光环化活性可以通过周围聚合物的刚性来调节。半结晶聚合物中的软非晶区有利于分子内运动，从而实现弱蓝色发射和高光环化活性，而刚性结晶相则限制了分子内运动，导致强烈的蓝色发射和低光反应性。同时，在结晶过程中，聚合物链在晶体生长边界层中的动态运动进一步加速了 TPE 的分子内运动，从而增强了在结晶区和非晶区的光反应性。以运动为主导的荧光使得 TPE 可以作为智能分子机器人，通过聚合物结晶产生所需的荧光图案。我们的发现提供了微观分子运动和宏观光学信号之间的相关性。
