Chinese Journal of Catalysis ›› 2026, Vol. 87: 206-216.DOI: 10.1016/S1872-2067(26)65102-9

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Tweaking the electron push-pull effect of vinylene-linked thienothiophene covalent organic frameworks for enhanced selective photocatalysis

Keke Zhanga, Fulin Zhanga, Yuexin Wanga, Fengwei Huanga, Kanghui Xionga, Xiang-Kui Gub, Xianjun Langa,*()   

  1. a Hubei Key Laboratory on Organic and Polymeric Optoelectronic Materials, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, China
    b School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, Hubei, China
  • Received:2025-12-18 Accepted:2026-01-21 Online:2026-08-18 Published:2026-06-24
  • Supported by:
    National Natural Science Foundation of China(22372124)

Abstract:

Covalent organic frameworks (COFs) unveil exceptional potential for selective photocatalysis, owing to their molecularly tunable structures. Herein, four COFs are designed with vinylene-linked isomeric thienothiophenes. Thereby, the condensation of 4,7-bis(2,6-dimethylpyridin-4-yl)benzo[c] [1,2,5]thiadiazole (MPBTD) and 4,7-bis(2,6-dimethylpyridin-4-yl)benzo[c][1,2,5]oxadiazole (MPBO) with thieno[3,2-b]thiophene-2,5-dicarbaldehyde (T32T) and thieno[2,3-b]thiophene- 2,5-dicarbaldehyde (T23T) yields MPBTD-T32T-COF, MPBTD-T23T-COF, MPBO-T32T-COF, and MPBO-T23T-COF, respectively. Comprehensive characterizations and theoretical calculations confirm the well-defined crystalline porous structures and distinct optoelectronic properties of these four COFs. Notably, the electron-withdrawing units, benzo[c][1,2,5]thiadiazole and benzo[c][1,2,5]oxadiazole, tweak the electron push-pull effect of COFs, leading to distinct photocatalytic performances. In the selective photocatalytic oxidation of three sulfide substrates, the observed performance exhibits the following order: MPBTD-T32T-COF > MPBTD-T23T-COF > MPBO-T32T-COF > MPBO-T23T-COF. Mechanistic studies reveal that superoxide is the predominant reactive oxygen species powering the selective photocatalytic sulfoxidation over MPBTD-T32T-COF. Furthermore, MPBTD-T32T-COF demonstrates recyclability and broad substrate applicability for the selective photocatalytic sulfoxidation.

Key words: Covalent organic frameworks, Full conjugation, Superoxide, Photocatalytic oxidation, Organic sulfides