Rational design of a phenothiazine-based donor-acceptor covalent organic framework for enhanced photocatalytic oxidative coupling of amines and cyclization of thioamides

Owing to the high structural designability and functional tunability, covalent organic frameworks (COFs) have emerged as a promising platform for designing excellent photocatalyst candidates. However, their photocatalytic performances are still hindered by insufficient separation and transfer of pho...

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Published in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2023-01, Vol.11 (3), p.128-1215
Main Authors: Liu, Yang, Jiang, Xinyue, Chen, Likun, Cui, Yan, Li, Qiu-Yan, Zhao, Xinsheng, Han, Xiguang, Zheng, Yong-Chao, Wang, Xiao-Jun
Format: Article
Language:English
Subjects:
Amines
Charge transfer
Current carriers
Energy charge
Excitons
Heterostructures
Phenothiazine
Photocatalysis
Photocatalysts
Photoexcitation
Separation
Structure-function relationships
Thiadiazoles
Triazine
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Summary:Owing to the high structural designability and functional tunability, covalent organic frameworks (COFs) have emerged as a promising platform for designing excellent photocatalyst candidates. However, their photocatalytic performances are still hindered by insufficient separation and transfer of photo-generated charge carriers. The ordered alignment of the electron donor (D) and acceptor (A) in two-dimensional COFs can promote charge carrier separation upon photoexcitation and provide a favorable pathway for exciton transport, and thus is advantageous for photocatalysis. In this work, we report a new D-A COF that was constructed from the electron-rich phenothiazine (PTZ) and electron-deficient triazine (TTA) subunits, giving rise to a segregated bicontinuous D-A heterostructure within the framework. In comparison to the triphenylamine (TPA) based analogue COF with smaller D-A contrast, this newly designed PTZ-TTA-COF exhibited lower exciton binding energy and enhanced charge separation/transfer. As a consequence, it revealed remarkably enhanced photocatalytic ability in oxidative amine coupling and cyclization of thioamide to 1,2,4-thiadiazole reactions under visible light and in air. This study will provide a rational guidance for developing high-performance polymeric photocatalysts based on D-A structural COFs through the molecular-level design strategy. A PTZ-based D-A COF with low exciton binding energy and high charge separation efficiency exhibited an enhanced photocatalytic performance in oxidative amine coupling and cyclization of thioamide reactions.
ISSN:2050-7488
2050-7496
DOI:10.1039/d2ta07177k