Volume 64, Issue 30 e202509095
Research Article

Enantioselective Immobilization of Nonprecious Metal Complexes on Chiral Covalent Organic Frameworks for Improved Single-Site Photocatalytic Hydrogen Evolution

Xingye Huang

Xingye Huang

State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200438 China

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Wanting Xie

Wanting Xie

State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200438 China

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Tiantian Xu

Tiantian Xu

State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200438 China

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Weijun Weng

Weijun Weng

State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200438 China

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Dr. Ting Zhou

Corresponding Author

Dr. Ting Zhou

State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200438 China

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

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Dr. Prof. Jia Guo

Corresponding Author

Dr. Prof. Jia Guo

State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200438 China

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

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First published: 19 May 2025

Graphical Abstract

Enantioselective immobilization of chiral Co(salen) complexes on the surface of chiral β-ketoenamine-linked COFs enables axial coordination of Co(II) centers with COF linkages, which tautomerize from keto-enamine to enol-imine upon binding. This enantiomeric assembly enhances Co(II) reducibility and allows for inner-sphere electron transfer, leading to remarkable photocatalytic H₂ evolution without additional precious metals.

Abstract

The noncovalent assembly of molecular catalysts into photocatalytic systems represents a pivotal strategy for exploring single-site heterogenous catalysts, excluding the need for elaborate functionalization design. However, the reliance on weak noncovalent interactions (e.g., van der Waals forces) often leads to inefficient outer-sphere electron transfer and inferior structural stability. Herein, we report the enantioselective immobilization of cobalt-based molecular catalysts with chiral tetradentate ligands onto the surface of a β-ketoenamine-linked chiral covalent organic framework (COF) synthesized through chirality induction. The enantiomeric assembly enables axial coordination between the molecular catalysts and the chiral COF, accompanied by enamine-to-imine tautomerization. Leveraging efficient inner-sphere electron transfer, the resulting composite exhibits a significantly enhanced H2 evolution rate (5.70 mmol g−1 h−1) and sustained performance without the use of precious metals. The enantiomeric assembly strategy on a COF platform demonstrates a viable approach to improve both the stability and activity of molecular catalysts, thereby expanding the design paradigm of single-site photocatalysts.

Conflict of Interests

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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