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1. Node-Assisted PhotoredoxReactivity Enables MOF-CatalyzedHydrogen/Deuterium Exchange in Aromatic Aldehydes

   https://doi.org/10.1021/jacs.6c08975  

   Lessard, Jacob M; McCormick, Farrah S; Bu, Chenjiao; Tinnell, Taylor N; Bowen, Jeffrey; Huang, Hongliang; Remcho, Vincent T; Huang, Liangliang; Stylianou, Kyriakos C (August 2026, Journal of the AmericanChemical Society)

   Abstract Light-driven isotopic labeling is currently dominated by homogeneous catalysis and largely relies on separate thiol-based hydrogen-atom-transfer catalysts. Metal–organic frameworks (MOFs), with their modular structures, confined pore environments, and tunable optoelectronic properties, offer an attractive but largely unexplored heterogeneous platform for controlled isotopic incorporation in chemicals. Herein, we report a systematic investigation of MOF-photocatalyzed hydrogen/deuterium (H/D) exchange, demonstrating that UiO-66-type materials uniquely enable thiol-free, formyl-selective deuteration of aromatic aldehydes using D2O as the sole deuterium source. Under UV irradiation, UiO-66 materials achieve up to 97% H/D incorporation over 3 h with 99% product selectivity, a level of control far surpassing that of catalyst-free photochemistry. Evaluation of the influence of linker functionalization shows that efficiency depends on multiple interdependent parameters, including radical generation, porosity, substrate binding and diffusion, and D2O accessibility, thereby establishing it as a key design handle for controlling reactivity in H/D exchange. Mechanistic investigations using electron paramagnetic resonance spectroscopy, controls using isotopically enriched UiO-66 and zirconium oxo clusters, and density functional theory analysis demonstrate that the Zr6O4(OH)4 nodes actively participate in catalysis, enabling deuterium transfer via proton-coupled electron-transfer mechanisms involving in situ-generated μ3-OD groups. Aldehyde confinement at the Zr6-cluster surface suppresses competing oxidation pathways and promotes a surface-confined radical mechanism that is inaccessible to homogeneous photocatalysts. Our findings establish UiO-66 as a single-component heterogeneous photocatalyst for selective isotopic labeling and mechanistically probe a previously unexplored mode of node-centered photoreactivity in MOFs. This work provides mechanistic insights into the use of MOFs for isotopic labeling and late-stage functionalization under mild conditions, highlighting the role of node-centered photochemistry. 

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2. Impact of Grafting Density on the Assembly and Mechanical Properties of Self-Assembled Metal–Organic Framework Monolayers

   https://doi.org/10.1021/jacs.4c17748  

   Kang, Minjung; Lin, Po-An; Bunch, Jordan A; Lipomi, Darren J; Arya, Gaurav; Cohen, Seth M (February 2025, Journal of the American Chemical Society)

   Polymer-grafted metal−organic frameworks (MOFs) can be used to form free-standing self-assembled MOF monolayers (SAMMs). Polymer chains can be introduced onto MOF surfaces through either the ligands or metal nodes using both grafting-to and grafting-from approaches. However, controlling the grafting density of polymer-grafted MOFs has not yet been achieved, because a means to control the density of grafting sites on the MOF surface has not been developed. In this study, the grafting density of polymer-grafted UiO-66 (UiO = University of Oslo) was controlled by functionalizing a portion of the Zr(IV) secondary building units (SBUs) on a UiO-66 surface with a so-called blocking agent. The remaining sites on the UiO-66 SBUs were functionalized with polymerization initiation groups, and polymers were grown from these sites to obtain particles with variable grafting densities and chain lengths that form SAMMs at an air−water interface. Even under conditions of low grafting density, these materials retain the ability to form SAMMs and their freestanding ability. Changes in particle arrangement within the monolayers were investigated using SEM imaging, and the toughness of the monolayers was evaluated using a film-on-water (FOW) method. Furthermore, coarse-grained molecular dynamics simulations were carried out to elucidate the morphology and mechanical properties of the monolayers. Findings from both experiments and simulations indicate that the toughness of SAMMs is more heavily influenced by the chain length of the grafted polymers than by the overall polymer content in the composite. 

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3. Designing optimal core–shell MOFs for direct air capture

   https://doi.org/10.1039/D2NR03177A  

   Boone, Paul; He, Yiwen; Lieber, Austin R.; Steckel, Janice A.; Rosi, Nathaniel L.; Hornbostel, Katherine M.; Wilmer, Christopher E. (November 2022, Nanoscale)

   Metal–organic frameworks (MOFs), along with other novel adsorbents, are frequently proposed as candidate materials to selectively adsorb CO 2 for carbon capture processes. However, adsorbents designed to strongly bind CO 2 nearly always bind H 2 O strongly (sometimes even more so). Given that water is present in significant quantities in the inlet streams of most carbon capture processes, a method that avoids H 2 O competition for the CO 2 binding sites would be technologically valuable. In this paper, we consider a novel core–shell MOF design strategy, where a high-CO 2 -capacity MOF “core” is protected from competitive H 2 O-binding via a MOF “shell” that has very slow water diffusion. We consider a high-frequency adsorption/desorption cycle that regenerates the adsorbents before water can pass through the shell and enter the core. To identify optimal core–shell MOF pairs, we use a combination of experimental measurements, computational modeling, and multiphysics modeling. Our library of MOFs is created from two starting MOFs-UiO-66 and UiO-67-augmented with 30 possible functional group variations, yielding 1740 possible core–shell MOF pairs. After defining a performance score to rank these pairs, we identified 10 core–shell MOF candidates that significantly outperform any of the MOFs functioning alone. 

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4. Unexpected Impacts of CO ₂ /H ₂ O Adsorption Order on the Mixed-Gas Adsorption Capacity of a Metal–Organic Framework

   https://doi.org/10.1021/jacs.5c08171  

   Hastings, Jon; Wang, Zhiwei; Liu, Jiayang; Formalik, Filip; Xie, Haomiao; Lassitter, Thomas; Farha, Omar K; Snurr, Randall Q; Hupp, Joseph T; Glover, T Grant (October 2025, Journal of the American Chemical Society)

   Metal-organic frameworks (MOFs) have been examined extensively for CO2 capture, and the influence of water co-adsorption on these processes is particularly relevant, as CO2 capture generally occurs in humid gas streams. To investi-gate CO2/H2O co-adsorption, binary adsorption isotherms of CO2 and H2O were measured on MOF-808-TFA (TFA = trifluoro-acetic acid). When water was pre-adsorbed on MOF-808-TFA, and a subsequent CO2 adsorption isotherm was measured, the CO2 adsorption was slightly reduced, as expected. However, when CO2 was adsorbed first and then an H2O adsorption iso-therm was measured, no significant H2O adsorption capacity was observed. The near complete loss of water adsorption ca-pacity was observed even when only a trace amount of CO2 was pre-adsorbed. The results show that unexpected, non-state function adsorption equilibria can result from dynamic MOF behaviors and defect sites, which may lead to counterintuitive adsorption data compared to traditional materials. 

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5. Exploring the Effect of Framework Flexibility on Water Adsorption in the Metal–Organic Framework NbOFFIVE-1-Ni Using Molecular Modeling

   https://doi.org/10.1021/acs.jpcc.4c04486  

   Daglar, Hilal; Keskin, Seda; Snurr, Randall Q (November 2024, The Journal of Physical Chemistry C)

   Many metal-organic frameworks (MOFs) are known to show complex structural flexibility such as breathing, swelling, and linker rotations, and understanding the impact of these structural changes on their guest adsorption properties is important in developing MOFs for practical applications. In this study, we used a multi-scale computational approach to provide a molecular-level understanding of how flexibility affects water adsorption in the MOF, NbOFFIVE-1-Ni. This material has narrow pores and good hydrothermal stability, which make it attractive for CO2 capture. We utilized density functional theory (DFT) calculations and grand canonical Monte Carlo (GCMC) simulations to study the impact of NbOFFIVE-1-Ni structural flexibility on its water adsorption at different humidity conditions. Studying the water adsorption in different configurations of NbOFFIVE-1-Ni demonstrated that DFT optimization in the presence of adsorbed water molecules and rotating the linkers are useful strategies to mimic its structural flexibility. Our results illustrate the significance of taking structural flexibility into account when designing MOFs for water adsorption and other relevant applications. 

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