Nanoscale Metal–Organic Framework Overcomes Hypoxia for Photodynamic Therapy Primed Cancer Immunotherapy

Immunotherapy has become a promising cancer therapy, but only works for a subset of cancer patients. Immunogenic photodynamic therapy (PDT) can prime cancer immunotherapy to increase the response rates, but its efficacy is severely limited by tumor hypoxia. Here we report a nanoscale metal–organic framework, Fe-TBP, as a novel nanophotosensitizer to overcome tumor hypoxia and sensitize effective PDT, priming non-inflamed tumors for cancer immunotherapy. Fe-TBP was built from iron-oxo clusters and porphyrin ligands and sensitized PDT under both normoxic and hypoxic conditions. Fe-TBP mediated PDT significantly improved the efficacy of anti-programmed death-ligand 1 (α-PD-L1) treatment and elicited abscopal effects in a mouse model of colorectal cancer, resulting in >90% regression of tumors. Mechanistic studies revealed that Fe-TBP mediated PDT induced significant tumor infiltration of cytotoxic T cells

Electron Injection from Photoexcited Metal–Organic Framework Ligands to Ru₂ Secondary Building Units for Visible-Light-Driven Hydrogen Evolution

We report the design of two new metal–organic frameworks (MOFs), Ru-TBP and Ru-TBP-Zn, based on Ru₂ secondary building units (SBUs) and porphyrin-derived tetracarboxylate ligands. The proximity of Ru₂ SBUs to porphyrin ligands (∼1.1 nm) facilitates multielectron transfer from excited porphyrins to Ru₂ SBUs to enable efficient visible-light-driven hydrogen evolution reaction (HER) in neutral water. Photophysical and electrochemical studies revealed oxidative quenching of excited porphyrin by Ru₂ SBUs as the initial step of the HER process and the energetics of key intermediates in the catalytic cycle. Our work provides a new strategy to building multifunctional MOFs with synergistic ligands and SBUs for efficient photocatalysis

Electron Injection from Photoexcited Metal–Organic Framework Ligands to Ru₂ Secondary Building Units for Visible-Light-Driven Hydrogen Evolution

We report the design of two new metal–organic frameworks (MOFs), Ru-TBP and Ru-TBP-Zn, based on Ru₂ secondary building units (SBUs) and porphyrin-derived tetracarboxylate ligands. The proximity of Ru₂ SBUs to porphyrin ligands (∼1.1 nm) facilitates multielectron transfer from excited porphyrins to Ru₂ SBUs to enable efficient visible-light-driven hydrogen evolution reaction (HER) in neutral water. Photophysical and electrochemical studies revealed oxidative quenching of excited porphyrin by Ru₂ SBUs as the initial step of the HER process and the energetics of key intermediates in the catalytic cycle. Our work provides a new strategy to building multifunctional MOFs with synergistic ligands and SBUs for efficient photocatalysis

Single-Site Cobalt Catalysts at New Zr₈(μ₂‑O)₈(μ₂‑OH)₄ Metal-Organic Framework Nodes for Highly Active Hydrogenation of Alkenes, Imines, Carbonyls, and Heterocycles

We report here the synthesis of robust and porous metal–organic frameworks (MOFs), M-MTBC (M = Zr or Hf), constructed from the tetrahedral linker methane-tetrakis­(<i>p</i>-biphenylcarboxylate) (MTBC) and two types of secondary building units (SBUs): cubic M₈(μ₂-O)₈(μ₂-OH)₄ and octahedral M₆(μ₃-O)₄(μ₃-OH)₄. While the M₆-SBU is isostructural with the 12-connected octahedral SBUs of UiO-type MOFs, the M₈-SBU is composed of eight M^IV ions in a cubic fashion linked by eight μ₂-oxo and four μ₂-OH groups. The metalation of Zr-MTBC SBUs with CoCl₂, followed by treatment with NaBEt₃H, afforded highly active and reusable solid Zr-MTBC-CoH catalysts for the hydrogenation of alkenes, imines, carbonyls, and heterocycles. Zr-MTBC-CoH was impressively tolerant of a range of functional groups and displayed high activity in the hydrogenation of tri- and tetra-substituted alkenes with TON > 8000 for the hydrogenation of 2,3-dimethyl-2-butene. Our structural and spectroscopic studies show that site isolation of and open environments around the cobalt-hydride catalytic species at Zr₈-SBUs are responsible for high catalytic activity in the hydrogenation of a wide range of challenging substrates. MOFs thus provide a novel platform for discovering and studying new single-site base-metal solid catalysts with enormous potential for sustainable chemical synthesis