Volume 64, Issue 28 e202506309
Research Article

p–π Conjugation-Promoted Electrochemiluminescence of Halogenated Covalent Organic Framework Nanoemitters

Hanlin Hou

Hanlin Hou

State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 China

School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, 637371 Singapore

These authors contributed equally to this work.

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Yuting Wu

Yuting Wu

State Key Laboratory of Precision and Intelligent Chemistry, Hefei National Laboratory, School of Chemistry and Material Sciences, CAS Key Laboratory of Materials for Energy Conversion, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, Hefei, 230026 China

These authors contributed equally to this work.

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Jiacheng Wan

Jiacheng Wan

State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 China

These authors contributed equally to this work.

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Dr. Rengan Luo

Dr. Rengan Luo

State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 China

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Prof. Dr. Lina Wu

Corresponding Author

Prof. Dr. Lina Wu

State Key Laboratory of Microbial Technology, School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023 China

E-mail: [email protected]; [email protected]; [email protected]; [email protected]

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Prof. Dr. Yanli Zhao

Corresponding Author

Prof. Dr. Yanli Zhao

School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, 637371 Singapore

E-mail: [email protected]; [email protected]; [email protected]; [email protected]

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Prof. Dr. Xiaojun Wu

Corresponding Author

Prof. Dr. Xiaojun Wu

State Key Laboratory of Precision and Intelligent Chemistry, Hefei National Laboratory, School of Chemistry and Material Sciences, CAS Key Laboratory of Materials for Energy Conversion, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, Hefei, 230026 China

E-mail: [email protected]; [email protected]; [email protected]; [email protected]

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Prof. Dr. Jianping Lei

Corresponding Author

Prof. Dr. Jianping Lei

State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 China

E-mail: [email protected]; [email protected]; [email protected]; [email protected]

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First published: 02 May 2025

Graphical Abstract

We design a series of halogenated COF nanoemitters via a covalent halogenation predesign strategy. The introduction of halogen atoms facilitates p–π conjugation within COF skeleton, leading to a 49-fold ECL enhancement compared to nonhalogenated COF. Furthermore, the performance of four partially brominated COFs establishes a positive correlation between the degree of Br doping and ECL intensity.

Abstract

Covalent organic frameworks (COFs) are a kind of promising electrochemiluminescence (ECL) crystalline nanoemitters due to their rapid intrareticular charge transfer and predesigned structures. However, the high polarization of heteroatom-containing linkages impedes the charge transfer within reticular structures. In this study, we construct a series of halogenated COFs nanoemitters composed of terephthalaldehyde ortho-substitutions and 1,3,6,8-tetrakis(4-aminophenyl)pyrene ligands via a covalent halogenation predesign strategy. The incorporation of covalently bonded halogen atoms promotes a dense electron population in carbon–carbon antibonding molecular orbitals, thereby facilitating efficient p–π conjugation within the COF structure. Based on the improved intrareticular charge transfer along carbon skeleton, as evidenced by the Hall effect and terahertz spectroscopy, the brominated COF demonstrates a 49-fold enhancement in ECL intensity compared to nonhalogenated COF. Furthermore, the performance of four partially brominated COFs establishes a positive correlation between the degree of Br doping and ECL intensity. Beyond the corresponding model compounds, the conjugated frameworks of COFs significantly amplify the halogenation-induced enhancement effect. This halogenation-promoted p–π conjugation in reticular skeleton provides a universal strategy to sensitize crystalline nanoemitters for decoding ECL enhancement mechanism.

Conflict of Interests

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available in the Supporting Information of this article.

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