Tunable morphologies and emission of photosensitive supramolecular self-assemblies through positional and trans-cis isomerization.
Tunable morphologies and emission of photosensitive supramolecular self-assemblies through positional and trans-cis isomerization.
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DOI：
10.1039/c9nr09155f
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发表时间：
2020-01
期刊：
影响因子：
6.7
通讯作者：
Zeyang Ding;Yuping Zhang;Yu Gao;Bing Yang;Shimei Jiang
中科院分区：
文献类型：
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作者：
Zeyang Ding;Yuping Zhang;Yu Gao;Bing Yang;Shimei Jiang
氰基二苯乙烯单元作为光响应性超分子结构单元受到广泛关注，其结构和发光可以通过反-顺异构化来调节。一般来说，性质的变化与氰基芪的分子结构有关，这仍然是不可预测的，需要探索。本文设计了两种不同氰基位置的苯-1，3，5-三甲酰胺（BTA）氰基二苯乙烯衍生物，分别研究了单体态和聚集态反-顺光异构化过程中的发光和结构变化.在单体状态下，外接氰基的衍生物β-BTTPA在紫外光照射下表现出明显的荧光增强，而另一种衍生物α-BTTPA则表现出荧光猝灭。此外，β-BTTPA在聚集体形成后，形成纳米级的蓝绿色发光纤维，而α-BTTPA形成微米级的蓝色发光扁平带。更重要的是，也由反-顺光异构化驱动，自组装显示形态转变（带状/纤维到球体），这是由于光反应打破了系统的平衡。这种变化进一步有助于发射切换以及增强的疏水特性。
Cyanostilbene units are widely attractive as photoresponsive supramolecular building blocks whose structures and emission can be modulated by trans-cis isomerization. Generally, the change of properties is related to the molecular structure of cyanostilbene, which is still unpredictable and needs to be explored. Herein, two benzene-1,3,5-tricarboxamide (BTA) based cyanostilbene derivatives with different cyano positions have been designed to investigate the emission as well as structural changes during the trans-cis photoisomerization process in monomer and aggregation states, respectively. In the monomer state, the derivative with cyano groups at the outer position, β-BTTPA, exhibits obvious emission enhancement upon UV irradiation, while the other derivative (α-BTTPA) shows emission quenching. In addition, upon the formation of aggregates, β-BTTPA forms nano-level fibers with blue-green emission, but α-BTTPA forms micron-level flat ribbons with blue emission. More importantly, also driven by the trans-cis photoisomerization, the self-assemblies show morphological transitions (ribbons/fibers to spheres) due to the fact that the equilibrium of the system is broken by the photoreactions. Such changes further contribute to emission switching as well as enhanced hydrophobic properties.