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Tunable morphologies and emission of photosensitive supramolecular self-assemblies through positional and trans-cis isomerization.
Nanoscale ( IF 5.8 ) Pub Date : 2020-01-08 , DOI: 10.1039/c9nr09155f
Zeyang Ding 1 , Yuping Zhang , Yu Gao , Bing Yang , Shimei Jiang
Affiliation  

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.

中文翻译:

通过位置和反式顺式异构化,可调节的形态和光敏性超分子自组装体的发射。

氰基苯乙烯单元作为光响应性超分子构建基块具有广泛的吸引力,其结构和发射可通过反式-顺式异构化来调节。通常,性质的变化与氰基苯乙烯的分子结构有关,这仍然是无法预测的,需要探索。在本文中,已设计了两个具有不同氰基位置的基于苯-1,3,5-三甲酰胺(BTA)的氰基茂苯衍生物,分别研究了反式顺式光异构化过程中单体和聚集态的发射以及结构变化。在单体状态下,在外部位置带有氰基的衍生物β-BTTPA在紫外线照射下表现出明显的发射增强,而另一种衍生物(α-BTTPA)则表现出发射猝灭。另外,在形成骨料时,β-BTTPA形成具有蓝绿色发射的纳米级纤维,而α-BTTPA形成具有蓝色发射的微米级扁平带。更重要的是,同样受反式顺式光异构化的驱动,由于光反应破坏了系统的平衡,因此自组装体出现了形态学转变(色带/纤维向球体)。这种变化进一步有助于发射转换以及增强的疏水性。
更新日期:2020-01-08
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