Symmetric covalent organic frame-work(COF)photocatalysts gener-ally suffer from inefficient charge separation and short-lived photoex-cited states.By performing den-sity functional theory(DFT)and time-dependent density functional theory(TDDFT)calculations,we find that partial substitution with one or two substituents(N or NH2)in the linkage of the rep-resentative symmetric COF(N0-COF)gives rise to the separation of charge carriers in the result-ing COFs(i.e.,N1-COF,N2-COF,(NH2)1-N0-COF,and(NH2)2-N0-COF).Moreover,we also find that the energy levels of the highest oc-cupied crystal orbital(HOCO)and the lowest unoccupied crystal orbital(LUCO)of the N0-COF can shift away from or toward the vacuum level,depending on the electron-withdrawing or electron-donating characters of the substituent.Therefore,we propose that partial sub-stitution with carefully chosen electron-withdrawing or electron-donating substituents in the linkages of symmetric COFs can lead to efficient charge separation as well as appropriate HOCO and LUCO positions of the generated COFs for specific photocatalytic reactions.The proposed rule can be utilized to further boost the photocatalytic performance of many symmetric COFs.

Ting-Ting Liu;Xin-Ping Wu;Xue-Qing Gong

Key Laboratory for Advanced Materials and Joint International Research Laboratory for Precision Chem-istry and Molecular Engineering,Feringa Nobel Prize Scientist Joint Research Center,Centre for Com-putational Chemistry and Research Institute of Industrial Catalysis,School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China

化学物理学报（英文版）

[1]Ting-Ting Liu;Xin-Ping Wu;Xue-Qing Gong-.Substituent Effects on the Photocatalytic Properties of a Symmetric Covalent Organic Framework)[J].化学物理学报（英文版）,2022(04):647-654

photoex,cupied,HOCO,LUCO

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