Facile construction of fully sp<sup>2</sup>-carbon conjugated two-dimensional covalent organic frameworks containing benzobisthiazole units.

Wang, Yuancheng; Hao, Wenbo; Liu, Hui; Chen, Renzeng; Pan, Qingyan; Li, Zhibo; Zhao, Yingjie · Nat Commun · 2022

basic_science · Level V

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Abstract

Developing a facile strategy for the construction of vinylene-linked fully π-conjugated covalent organic frameworks (COFs) remains a huge challenge. Here, a versatile condition of Knoevenagel polycondensation for constructing vinylene-linked 2D COFs was explored. Three new examples of vinylene-linked 2D COFs (BTH-1, 2, 3) containing benzobisthiazoles units as functional groups were successfully prepared under this versatile and mild condition. The electron-deficient benzobisthiazole units and cyano-vinylene linkages were both integrated into the π conjugated COFs skeleton and acted as acceptor moieties. Interestingly, we found the construction of a highly ordered and conjugated D-A system is favorable for photocatalytic activity. BTH-3 with benzotrithiophene as the donor with a strong D-A effect exhibited an attractive photocatalytic HER of 15.1 mmol h<sup>-1</sup>g<sup>-1</sup> under visible light irradiation.