The selective activation of inert C-H bonds has been regarded as the “Holy Grail” of organic synthetic chemistry for over a century. These bonds-found in nearly all organic molecules-possess dissociation energies of approximately 440 kJ/mol for C(sp 3 )-H bonds, making them extremely difficult to cleave. Traditional industrial processes rely on high temperatures, high pressures, and toxic stoichiometric oxidants such as KMnO 4 and CrO 3 , generating large amounts of hazardous waste. Even worse, the desired oxidation products (such as aldehydes and ketones) are often more reactive than the starting materials, leading to overoxidation and poor selectivity.
Now, a team of researchers from Changchun University of Science and Technology and Jilin University has published a comprehensive review in Polyoxometalates on June 26, 2026, systematically summarizing how metal-organic frameworks (MOFs) and polyoxometalate-based MOFs (POMOFs) are revolutionizing photocatalytic C-H bond activation. The review covers a decade of progress in designing these atomically precise materials to overcome the long-standing activity-selectivity trade-off.
MOFs are crystalline porous materials constructed from metal nodes and organic linkers. Their modular nature allows researchers to integrate light-harvesting antennas, catalytic centers, and substrate-recognition sites within a single framework with atomic precision. “MOFs bridge the gap between homogeneous and heterogeneous catalysis,” explained Dr. Jing Sun, co-corresponding author of the review. “They offer the structural clarity of molecular catalysts combined with the recyclability and robustness of solid materials. The pore confinement effect also stabilizes reactive intermediates and provides unprecedented control over reaction selectivity.”
The review highlights a particularly powerful strategy: incorporating polyoxometalates (POMs)-inorganic metal-oxygen clusters with exceptional redox properties-into MOF pores to create POMOFs. POMs act as “electronic sponges,” capable of reversibly accepting and releasing multiple electrons without structural degradation. When integrated into MOFs, they enable ultrafast (picosecond-scale) electron injection from the light-excited framework, dramatically suppressing charge recombination and generating long-lived charge-separated states.
“Our analysis reveals that POMOFs are not simple physical mixtures but hybrid materials with strong electronic coupling between the host and guest,” said Dr. Xiao Li, co-corresponding author. “The POM's electron-sponge function synergizes with the MOF's light-absorption capability, opening up new pathways for generating reactive oxygen species such as superoxide radicals and singlet oxygen with high selectivity.”
The review systematically covers the activation of various C-H bond types, each presenting unique challenges. For aromatic C(sp 2 )-H bonds, MOF-based catalysts like MIL-100(Fe) enable efficient hydroxylation of benzene to phenol through photo-Fenton reactions. For benzylic C(sp 3 )-H bonds-which are ideal model substrates due to their lower bond energy (~85-90 kcal/mol)-catalysts such as EY@MOF-808 achieve selective oxidation of benzyl alcohol to benzaldehyde by leveraging host-guest interactions that preferentially bind the substrate over the product. Remarkably, the Ce-AQ MOF achieves over 98% selectivity for cyclohexanone in cyclohexane oxidation, surpassing conventional industrial processes.
Methane oxidation represents the ultimate challenge, with a C-H bond energy of 104 kcal/mol. The review highlights recent breakthroughs using defect-engineered MOFs with single-atom copper sites (Def-CuCN/NU), which achieve selective methane-to-methanol conversion under ambient conditions by suppressing overoxidation through rapid product desorption. “The trade-off between activating inert C-H bonds and avoiding overoxidation of reactive products is the core scientific challenge,” noted Professor Zhongmin Su, corresponding author. “MOFs and POMOFs provide a unique platform to address this because their pore environments can be precisely engineered to stabilize desired products and promote their release before further oxidation occurs.”
The review also discusses exciting applications beyond conventional oxidation, including cascade reactions that couple oxidation with nitrobenzene reduction to synthesize imines with atomic economy, and even biomedical applications where MOF-based photosensitizers selectively oxidize cancer cell membrane phospholipids to trigger programmed cell death.
Despite remarkable achievements, the authors identify several key challenges for future research. Understanding catalytic mechanisms under realistic operating conditions requires advanced operando characterization techniques, including time-resolved X-ray absorption and transient absorption spectroscopies. Scalable and green synthesis methods-such as aqueous-phase, mechanochemical, and continuous-flow approaches-need to be developed to translate laboratory discoveries into industrial applications. Professor Su added, “The integration of machine learning and artificial intelligence with structure-performance databases could accelerate the discovery of next-generation photocatalysts by enabling high-throughput virtual screening. The future of MOF/POMOF photocatalysts lies in becoming more intelligent, precise, and multifunctional.”
With the accumulation of structural databases and catalytic performance datasets, the authors are optimistic about the role of AI-assisted design in accelerating catalyst discovery. They predict that by harnessing unlimited sunlight through these molecular materials, highly stable C-H bonds can be transformed into complex molecular architectures, significantly contributing to a sustainable chemical industry and green synthesis paradigm.
Other contributors include Yanjie Lv, Xinyu Zhao, and Wenxi Zhang from Changchun University of Science and Technology. This work was supported by the National Natural Science Foundation of China (No. 22271023) and the Jilin Province Science and Technology Development Plan Project (No. YDZJ202502CXJD051).
D OI Link:
https://doi.org/10.26599/POM.2026.9140138
About the Authors
Dr. Zhongmin Su: Distinguished Professor and doctoral supervisor at Jilin University, Tang Aoqing Scholar. First-class professor of Jilin Province. National-level special-appointed professor for high-end talent, Outstanding Talent across the Century by the Ministry of Education; member of the Chemistry Discipline Evaluation Group of the State Council Academic Degrees Committee for the 6th and 7th terms. National Outstanding Backbone Teacher in Higher Education Institutions; recipient of the "National May 1st Labor Medal" awarded by the All-China Federation of Trade Unions, and a Special-Class Model Worker of Changchun City. His research focuses on integrating experimental and theoretical approaches in theoretical chemistry and computation, as well as functional materials chemistry. He has published 285 SCI-indexed papers in recent years, including in journals such as J. Am. Chem. Soc., Angew. Chem. Int. Ed., and Nature Commun. He has received the Second Prize of the National Natural Science Award, as well as the First Prizes of Natural Science and Scientific & Technological Progress from Jilin Province. He was listed among the Clarivate Global Highly Cited Researchers from 2014–2018 and 2022, and included in Elsevier's China Most Cited Scholars list from 2016 to 2025. He ranked among the top 0.05% of global scientists (lifetime) in the ScholarGPS 2024 ranking. He led the Innovation Team Project under the Ministry of Education’s Changjiang Scholars Program, and served as principal investigator for projects including the Ministry of Science and Technology’s “973 Program” predictive project, “863 Program” projects, and key projects of the National Natural Science Foundation of China. He previously served as part-time Vice Chairman of the Jilin Provincial Association for Science and Technology, councilor of the Chinese Chemical Society, and Vice President of the Jilin Chemical Society, as well as Director of the Jilin Provincial Center for Optical Materials and Chemical Science and Technology Innovation. He also served as Deputy Director of the Jilin Provincial Department of Education, Vice President of Northeast Normal University, and President of Changchun University of Science and Technology. Currently, he serves as Advisory Editorial Board Member of the journal Polyoxometalates, Chair of the 6th Council of the Jilin Provincial Education Foundation, and Deputy Chair of the Academic Committee of Jilin University.
Dr. Jing Sun: Professor and doctoral supervisor. Director of the Jilin Provincial Center for Innovation in Optical Materials and Chemical Technology, member of the Jilin Provincial Professional Degree Graduate Education Guidance Committee, member of the 7th Rare Earth Crystal Professional Committee of the Chinese Rare Earth Society, and standing council member of the Jilin Chemical Society. Her main research interests include optofunctional materials and chemistry. She has led or participated in over 20 research projects, with three currently underway. She is the first author of one published monograph and holds two authorized Chinese invention patents. She has published more than 50 SCI-indexed papers in journals such as Anal. Chem., Coord. Chem. Rev., Chem. Eng. J., J. Colloid Interface Sci., and J. Catal., including one highly cited and hot paper. She received the ICF Outstanding Paper Award for 2014–2023 and one third prize in Natural Science from Jilin Province (ranked first).
Dr. Xiao Li: Associate Professor and Master's thesis supervisor. Department Chair of the School of Chemistry and Environmental Engineering. She has long been engaged in the synthesis of metal-organic framework (MOF) materials and polyoxometalate (POM)-based composites, as well as their applications, including: (1) carbon-coated multi-component materials derived from bimetallic MOFs and POM@MOFs for electrocatalytic water splitting; (2) synthesis and studies on dye degradation, fluorescent sensing, and ion adsorption properties of multifunctional MOFs and MOF composites. In recent years, she has published over ten SCI-indexed papers as first or corresponding author in internationally renowned journals such as Adv. Funct. Mater., Chem. Eng. J., J. Catal., Chin. Chem. Lett., Polyoxometalates, Inorg. Chem., Dyes Pigm., and Int. J. Hydrogen Energ.
Dr. Yanjie Lv (first author): A 2024-level doctoral student, female. Currently studying at the College of Chemistry and Environmental Engineering of Changchun University of Science and Technology. Her research focuses on the design and synthesis of metal-organic framework structures based on multi-sulfonate, as well as the study of their photocatalytic properties. The research mainly involves the design and synthesis based on the regulation of metal type, coordination mode, and dimension, and its application in C-H bond oxidation studies. She has published multiple SCI papers in journals such as J. Catal., Chin. Chem. Lett., and Polyoxometalates.
About Journal
Polyoxometalates (ISSN 2957-9821) is a peer-reviewed (single-blind), open-access and interdisciplinary journal, sponsored by Tsinghua University. Polyoxometalates publishes original high-quality research papers and significant review articles that focus on cutting-edge advancements in Polyoxometalates, and clusters of metals, metal oxides and chalcogenides. Rapid review to ensure quick publication is a key feature of Polyoxometalates . The journal is indexed by ESCI (IF 2025 = 10.4, Top 3), Scopus (CiteScore 2025 = 17.6, Top 3), Ei Compendex, CAS, and DOAJ. For details about Polyoxometalates , please visit: https://www.sciopen.com/journal/2957-9821 .
Polyoxometalates
Recent progress in the development of MOFs/POMOFs for light-mediated C–H bond activation
26-Jun-2026