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We report here the design of two multifunctional metal−organic frameworks (MOFs), mPT-Cu/Co and mPT-Cu/Re , comprising cuprous photosensitizers (Cu-PSs) and molecular Co or Re catalysts for photocatalytic hydrogen evolution (HER) and CO2 reduction (CO2RR), respectively. Hierarchical organization of Cu-PSs and Co/Re catalysts in these MOFs facilitates multielectron transfer to drive HER and CO2RR under visible light with an HER turnover number (TON) of 18 700 for mPT-Cu/Co and a CO2RR TON of 1328 for mPT-Cu/Re, which represent a 95-fold enhancement over their homogeneous controls. Photophysical and electrochemical investigations revealed the reductive quenching pathway in HER and CO2RR catalytic cycles and attributed the significantly improved performances of MOFs over their homogeneous counterparts to enhanced electron transfer due to close proximity between Cu-PSs and active catalysts and stabilization of Cu-PSs and molecular catalysts by the MOF framework.

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Catalytic borylation has recently been suggested as a potential strategy to convert abundant methane to fine chemicals. However, synthetic utility of methane borylation necessitates significant improvement of catalytic activities over original phenanthroline- and diphosphine-Ir complexes. Herein, we report the use of metal–organic frameworks (MOFs) to stabilize low-coordinate Ir complexes for highly active methane borylation to afford the monoborylated product. The mono­(phosphine)-Ir based MOF, Zr-P1-Ir, significantly outperformed other Ir catalysts in methane borylation to afford CH3Bpin with a turnover number of 127 at 110 °C. Density functional theory calculations indicated a significant reduction of activation barrier for the rate limiting oxidative addition of methane to the four-coordinate (P1)­IrIII(Bpin)3 catalyst to form the six-coordinate (P1)­IrV(Bpin)3(CH3)­(H) intermediate, thus avoiding the formation of sterically encumbered seven-coordinate IrV intermediates as found in other Ir catalysts based on chelating phenanthroline, bipyridine, and diphosphine ligands. MOF thus stabilizes the homogeneously inaccessible, low-coordinate (P1)­Ir­(boryl)3 catalyst to provide a unique strategy to significantly lower the activation barrier for methane borylation. This MOF-based catalyst design holds promise in addressing challenging catalytic reactions involving highly inert substrates.

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We report here the synthesis of a series of metal−organic frameworks (MOFs), FeX@Zr 6 -Cu, comprising cuprous photosensitizing linkers (Cu-PSs) and catalytically active Fe II centers supported on secondary building units (SBUs) for photocatalytic H 2 evolution. Close proximity (∼1 nm) between Cu-PS and SBU-supported Fe sites and stabilization of Fe sites by periodically ordered SBUs led to exceptionally high H 2 evolution activity for FeX@Zr 6 -Cu, with turnover numbers of up to 33 700 and turnover frequencies of up to 880 h −1 . Photocatalytic H 2 evolution activities of FeX@Zr 6 -Cu correlate with the lability of X counteranions, suggesting that open coordination environments of Fe sites generated by labile X groups facilitate the formation of Fe-hydride intermediates before hydrogen evolution. This work highlights the potential of using MOFs to integrate Earth-abundant components for solar energy utilization.

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