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Updated: Sep 9, 2025
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Developing a Highly Reducing Heterogeneous Nickel Photocatalyst with Photoexcited Hantzsch Esters
Ming Cui1,2, Deyang Wang1, Jun Guo1,2
1Department of Chemistry, The University of Hong Kong, Hong Kong 999077, China.
Journal of the American Chemical Society
|September 1, 2025
Summary
This study introduces a novel nickel(I) photocatalyst within a covalent organic framework for efficient single-electron reductions. This earth-abundant metal catalyst offers a sustainable alternative for organic synthesis, demonstrating high recyclability and reduced catalyst loading.
Area of Science:
- Materials Science
- Catalysis
- Organic Chemistry
Background:
- Noble-metal complexes and organic molecules are common photocatalysts for alkyl halide reduction.
- Developing highly reducing photocatalysts from earth-abundant metals remains a challenge.
Purpose of the Study:
- To develop a heterogeneous photocatalyst based on earth-abundant metals for single-electron reduction.
- To investigate the performance of a nickel(I) complex integrated into a covalent organic framework.
Main Methods:
- Synthesized a terpyridine-ligated nickel(II) complex within an imine-linked covalent organic framework.
- Utilized photoexcited Hantzsch esters for the reduction of the nickel complex to nickel(I).
- Evaluated the photocatalyst's performance in reductive couplings of organohalides and allyl sulfones.
Main Results:
- Generated a heterogeneous nickel(I) photocatalyst with a low excited-state oxidation potential (~ -3.5 V vs SCE).
- Framework support and confinement effects enhanced photocatalyst stability and performance compared to homogeneous systems.
- Achieved reduced catalyst loadings and high recyclability in challenging reductive coupling reactions.
Conclusions:
- Framework-based heterogenization is a viable strategy for developing robust photoredox catalysts using earth-abundant metals.
- This nickel-based system offers a sustainable and practical approach to organic synthesis.
- The developed photocatalyst shows promise for promoting reductive couplings of challenging electrophiles.
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