The performance of covalent organic frameworks (COFs) as photocatalysts, grounded on light absorption and optoelectronic properties, can be precisely regulated by the building blocks. Thienothiophene is an electron-rich building block of choice for the construction of COFs. Herein, two thienothiophene-based COFs are constructed by the condensation of thieno[3,2-b]thiophene-2,5-dicarbaldehyde (TT) with 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT), respectively, affording TT-TAPB-COF and TT-TAPT-COF of high crystallinity as confirmed by powder X-ray diffraction and transmission electron microscopy. Compared to TT-TAPB-COF, TT-TAPT-COF delivers more effective light-triggered charge separation and migration because of the electron-deficient yet planar triazine in TAPT. As such, TT-TAPT-COF exhibits better performance than TT-TAPB-COF for the visible light-triggered oxidation of organic sulfides with molecular oxygen. Besides, blue light-triggered oxidation of many organic sulfides over the TT-TAPT-COF photocatalyst produces the corresponding sulfoxides with excellent conversions and selectivities. The exceptional stability of the TT-TAPT-COF photocatalyst is demonstrated by recycling experiments. Substantially, the reaction mechanism is investigated by quenching experiments and spectroscopic studies. This work provides insight into the rational design of COFs by configuring the electron donor–acceptor for the precise application in photocatalysis.

中文翻译：

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基于噻吩并噻吩的共价有机框架用于可见光触发硫化物氧化为亚砜


共价有机框架（COF）作为光催化剂的性能基于光吸收和光电特性，可以通过构建模块进行精确调节。噻吩并噻吩是一种用于构建 COF 的富电子结构单元。在此，通过噻吩并[3,2-b]噻吩-2,5-二甲醛（TT）与1,3,5-三（4-氨基苯基）苯（TAPB）和2的缩合构建了两个基于噻吩并噻吩的COF。 ,4,6-三(4-氨基苯基)-1,3,5-三嗪(TAPT)，分别提供高结晶度的TT-TAPB-COF和TT-TAPT-COF，经粉末X射线衍射和透射证实电子显微镜。与 TT-TAPB-COF 相比，由于 TAPT 中缺电子且平面的三嗪，TT-TAPT-COF 可提供更有效的光触发电荷分离和迁移。因此，TT-TAPT-COF 在可见光触发的有机硫化物与分子氧的氧化方面表现出比 TT-TAPB-COF 更好的性能。此外，TT-TAPT-COF 光催化剂上的蓝光触发氧化许多有机硫化物，产生相应的亚砜，具有优异的转化率和选择性。回收实验证明了 TT-TAPT-COF 光催化剂的卓越稳定性。实质上，反应机理是通过淬灭实验和光谱研究来研究的。这项工作通过配置电子供体-受体以实现光催化的精确应用，为 COF 的合理设计提供了见解。