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Metal-organic frameworks (MOFs) have great prospects as adsorbents for industrial gas purification, but often suffer from issues of water stability and competitive water adsorption. Herein, we present a hydrolytically stable MOF that could selectively capture and recover trace SO 2 from flue gas, and exhibits remarkable recyclability in the breakthrough experiments under wet flue-gas conditions, due to its excellent resistance to the corrosion of SO 2 and the water-derived capillary forces. More strikingly, its SO 2 capture efficiency is barely influenced by the increasing humidity, even if the pore filling with water is reached. Mechanistic studies demonstrate that the delicate pore structure with diverse pore dimensions and chemistry leads to different adsorption kinetics and thermodynamics as well as segregated adsorption domains of SO 2 and H 2 O. Significantly, this non-competitive adsorption mechanism enables simultaneous desulfurization and dehydration by a single adsorbent, opening an avenue toward cost-effective and simplified processing flowcharts for flue gas purification., (© 2024 Wiley-VCH GmbH.)

Lanthanide metal-organic frameworks (Ln-MOFs) are promising for luminescence detection of volatile organic compound (VOC) vapors, but usually suffer from the silent or quenched Ln 3+ emission. Herein, we report a new dual-emissive Eu-MOF composed of the coordinatively unsaturated Eu 9 clusters that afford abundant open metal sites to form a confined "binding pocket" to facilitate the preconcentration and recognition of VOCs. Single-crystal structural analyses reveal that specific analytes can replace the OH oscillators in the first coordination sphere of Eu 3+ and form a unique hydrogen-bonding second-sphere adduct tying adjacent Eu 9 clusters together to minimize their nonradiative vibrational decay. With the promoted Eu 3+ luminescence, the MOF realizes real-time in situ visual sensing of THF vapor (<1 s) and shows a quantitative ratiometric response to the vapor pressure with a limit of detection down to 17.33 Pa. Also, it represents a top-performing ratiometric luminescent thermometer., (© 2022 Wiley-VCH GmbH.)

Developing universal stimuli-responsive materials capable of emitting a broad spectrum of colors is highly desirable. Herein, we deliberately grafted a conformation-adaptable organic chromophore into the established coordination space of a flexible metal-organic framework (MOF). In terms of the coupled structural transformations and the space confinement, the chromophore in the MOF matrix underwent well-regulated conformational changes under physical and chemical stimuli, simultaneously displaying thermo-, piezo-, and solvato-fluoro-chromism with color tunability over the visible range. Owing to the resilient nature and the reduced dimensionality of the selected coordination space, all three color modulations behaved in a sensitive and self-reversible manner, each following a linear correlation of the emission maximum with stimulus. Single-crystal X-ray diffraction of the variable-temperature structures and solvent-inclusion crystals elucidated the intricate color varying mechanisms., (© 2022 Wiley-VCH GmbH.)

By virtue of combining an in-situ assembly process with a stepwise synthesis in conventional aqueous solution, two series of unique organic-inorganic hybrid heteropolyoxomolybdates were constructed from plenary Keggin germanomolybdates and Cu-Ln heterometallic units and fully characterized: [H 2 INA] 2 H 8 [LnCu(INA) 4 (H 2 O) 6 ] 2 [α-GeMo 12 O 40 ] 3 ⋅52 H 2 O (Ln=La 3+ (1), Ce 3+ (2), Pr 3+ (3), Nd 3+ (4), Sm 3+ (5), Eu 3+ (6); HINA=isonicotinic acid) and (NH 4 )[Cu(PA) 2 ][Cu(PA) 2 Ln(H 2 O) 8 ][α-GeMo 12 O 40 ]⋅10 H 2 O (Ln=Nd 3+ (7), Sm 3+ (8), Eu 3+ (9); HPA=picolinic acid). The most remarkable structural characteristic of compounds 1-6 was that their molecular units were defined by three discrete plenary Keggin [α-GeMo 12 O 40 ] 4- polyoxoanions and two organic-inorganic hybrid heterometallic [LnCu(INA) 4 (H 2 O) 6 ] + moieties, whereas compounds 7-9 exhibited a nice-looking 1D chain-like structure that was built from plenary [α-GeMo 12 O 40 ] 4- polyoxoanions, pendent [Cu(PA) 2 ] complexes, and bridging {[Cu(PA) 2 ][Ln(H 2 O) 8 ]} 3+ heterometallic groups. Notably, two different pyridine carboxylic acid ligands led to the discrepancy between the two structure types. To the best of our knowledge, compounds 1-9 constitute the first examples of plenary Keggin heterometallic germanomolybdates that include Cu-Ln-organic subunits. Further studies revealed that compounds 3 and 8 exhibited fast adsorption capacity for cationic dyes methylene blue (MB) and rhodamine B (RhB) in water. Moreover, compounds 3 and 8 could quickly and selectively adsorb MB from a mixture of MB/methyl orange (MO) or MB/azophloxine (Apo)., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)