Search

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 SO2 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 SO2 and the water‐derived capillary forces. More strikingly, its SO2 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 SO2 and H2O. 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. [ABSTRACT FROM AUTHOR]

Separation of the mixture of ethylene (C2H4) and ethane (C2H6) to produce polymer-grade C2H4 is of prime importance in the petrochemical industry. In this context, metal–organic frameworks (MOFs) featuring tunable pore metrics and surface chemistry, especially those with inverse C2H6/C2H4 adsorption selectivity, hold great promise in energy-effective purification of C2H4 by adsorptive separation, but often encounter the well-known trade-off between adsorption selectivity and capacity. In this work, we report two new MOFs by deploying the pore-space-partition (PSP) strategy for the purpose of reducing the pore aperture size while retaining the gas-accessible pore volume. As a result, Ni-bodc-tpt (bodc = bicyclo[2.2.2]octane-1,4-dicarboxylic acid, tpt = 2,4,6-tri(4-pyridyl)-1,3,5-triazine) by combining optimal pore size, large cage pore volume, and rich C–H binding sites exhibits concurrently high C2H6 adsorption capacity (131.65 cm3 g−1) and C2H6/C2H4 selectivity (1.8) at 298 K and 1 bar, which is superior or comparable to many benchmark C2H6-selective MOFs. A dynamic breakthrough experiment demonstrates that high-purity C2H4 (>99.9%) can be harvested in one step from a binary mixture of C2H6/C2H4 (50/50, v/v), attesting to the feasibility of this new MOF as a prospective C2H4 purification agent. [ABSTRACT FROM AUTHOR]

Purifying olefin from ternary paraffin/olefin/alkyne mixtures through a one‐step adsorption process is extremely desirable. Herein, a stable zirconium(IV) metal‐organic framework with a customized pore surface composed of nonpolar phenyl and slightly polar thiophene rings is reported to access the adsorption preference of paraffin and alkyne over olefin. Noteworthily, this material displays a superior ability to discriminate C3 hydrocarbon molecules, which is principally more challenging compared with C2 ones and rarely documented. Computational studies disclose that its featured pore shape fits well with C3 gas molecules, enabling them to get close contact with the immobilized affinity sites. Leveraging surface chemistry and pore shape engineering synergistically gives rise to excellent C3 adsorption capacities (>5 mmol g−1) and concurrently high C3H8/C3H6 (1.4) and C3H4/C3H6 (1.9) selectivities (at 298 K and 1 atm). Dynamic column breakthrough experiments demonstrate that one‐step purification of C2H4 and C3H6 can be simultaneously realized on this material. [ABSTRACT FROM AUTHOR]

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 Ln3+ emission. Herein, we report a new dual‐emissive Eu‐MOF composed of the coordinatively unsaturated Eu9 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 Eu3+ and form a unique hydrogen‐bonding second‐sphere adduct tying adjacent Eu9 clusters together to minimize their nonradiative vibrational decay. With the promoted Eu3+ 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. [ABSTRACT FROM AUTHOR]

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.)