Converting CO into fuels via photochemical reactions relies on highly efficient and selective catalysts. We demonstrate that the catalytic active metal center can cooperate with neighboring hydroxide ligands to boost the photocatalytic CO reduction. Six cobalt-based metal-organic frameworks (MOFs) with different coordination environments are studied at the same reaction condition (photosensitizer, electron donor, water/organic mixed solvent, and visible light). In pure CO at 1.0 atm, the MOFs bearing μ-OH ligands neighboring the open Co centers showed CO selectivities and turnover frequencies (TOFs) up to 98.2% and 0.059 s, respectively. More importantly, their TOFs reduced only ca. 20% when the CO partial pressure was reduced to 0.1 atm, while other MOFs reduced by at least 90%. Periodic density functional theory calculations and isotope tracing experiments showed that the μ-OH ligands serve not only as strong hydrogen-bonding donors to stabilize the initial Co-CO adduct but also local proton sources to facilitate the C-O bond breaking.
Efficient adsorptive separation of propylene/propane (C 3 H 6 /C 3 H 8 )i sh ighly desired and challenging.K nown strategies focus on either the thermodynamic or the kinetic mechanism. Here,w er eport an interesting reactivity of am etal-organic framework that improves thermodynamic and kinetic adsorption selectivity simultaneously.W hen the metal-organic framework is heated under oxygen flow, half of the soft methylene bridges of the organic ligands are selectively oxidized to form the more polar and rigid carbonyl bridges. Mixture breakthrough experiments showed drastic increase of C 3 H 6 /C 3 H 8 selectivity from 1.5 to 15. Forc omparison, the C 3 H 6 /C 3 H 8 selectivities of the best-performing metal-organic frameworks Co-MOF-74 and KAUST-7 were experimentally determined to be 6.5 and 12, respectively.G as adsorption isotherms/kinetics,s ingle-crystal X-ray diffraction, and computational simulations revealed that the oxidation gives additional guest recognition sites,w hich improve thermodynamic selectivity,a nd reduces the framework flexibility,w hich generate kinetic selectivity.
The results of this study suggest that salvage liver resection after downstaging of unresectable hepatocellular carcinoma in patients with a complete response to transarterial chemoembolization (TACE) has a comparable long-term outcome in this good-prognosis group. Salvage liver resection may provide a better long-term outcome compared with TACE alone, but only in patients with macroscopic vascular invasion or those with a partial response to TACE.
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