Adsorptive separation of acetylene (C2H2) from carbon dioxide (CO2) promises a practical way to produce high-purity C2H2 required for industrial applications. However, challenges exist in the pore environment engineering of porous materials to recognize two molecules due to their similar molecular sizes and physical properties. Herein, we report a strategy to optimize pore environments of multivariate metal–organic frameworks (MOFs) for efficient C2H2/CO2 separation by tuning metal components, functionalized linkers, and terminal ligands. The optimized material UPC-200­(Al)-F-BIM, constructed from Al3+ clusters, fluorine-functionalized organic linkers, and benzimidazole terminal ligands, demonstrated the highest separation efficiency (C2H2/CO2 uptake ratio of 2.6) and highest C2H2 productivity among UPC-200 systems. Experimental and computational studies revealed the contribution of small pore size and polar functional groups on the C2H2/CO2 selectivity and indicated the practical C2H2/CO2 separation of UPC-200­(Al)-F-BIM.

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Ethylene (C 2 H 4 ) and propylene (C 3 H 6 ) are important energy sources and raw materials in the chemical industry. Storage and separation of C 2 H 4 and C 3 H 6 are vital to their practical application. Metal–organic frameworks (MOFs) having adjustable structures and pore environments are promising candidates for C 3 H 6 /C 2 H 4 separation. Herein, we obtained a Cu-based MOF synthesized by H 3 TTCA and pyrazine ligands. By adding different functional groups on the ligands within the MOFs, their pore environments are adjusted, and thus, the C 3 H 6 storage capacity and C 3 H 6 /C 2 H 4 separation efficiency are improved. Eventually, the fluoro- and methyl-functionalized iso-MOF-4 exhibits a better gas storage and C 3 H 6 /C 2 H 4 separation performance compared with iso-MOF-1 (nonfunctionalized), iso-MOF-2 (fluoro-functionalized), and iso-MOF-3 (methyl-functionalized). A record-high C 3 H 6 uptake of 293.6 ± 2.3 cm 3 g –1 (273 K, 1 atm) is achieved using iso-MOF-4 . Moreover, iso-MOF-4 shows excellent repeatability, and only 3.5% of C 3 H 6 storage capacities decrease after nine cycles. Employing Grand Canonical Monte Carlo (GCMC) simulations, it is indicated that iso-MOF-4 preferentially adsorbs C 3 H 6 rather than C 2 H 4 at low pressure. Single-crystal X-ray diffraction on C 3 H 6 -adsorbed iso-MOF-4 crystals precisely demonstrates the adsorption positions and arrangement of C 3 H 6 molecules in the framework, which is consistent with the theoretical simulations. Remarkably, gas sorption isotherms, molecular simulations, and breakthrough experiments comprehensively demonstrate that this unique MOF material exhibits highly efficient C 3 H 6 /C 2 H 4 separation. Additionally, iso-MOF-4 also possesses efficient separation of C 3 H 8 /CH 4 and C 2 H 6 /CH ...

The ever-increasing concerns over indoor/outdoor air quality, industrial gas leakage, food freshness, and medical diagnosis require miniaturized gas sensors with excellent sensitivity, selectivity, stability, low power consumption, cost-effectiveness, and long lifetime. Metal-organic frameworks (MOFs), featuring structural diversity, large specific surface area, controllable pore size/geometry, and host-guest interactions, hold great promises for fabricating various MOF-based devices for diverse applications including gas sensing. Tremendous progress has been made in the past decade on the fabrication of MOF-based sensors with elevated sensitivity and selectivity toward various analytes due to their preconcentrating and molecule-sieving effects. Although several reviews have recently summarized different aspects of this field, a comprehensive review focusing on MOF-based gas sensors is absent. In this review, the latest advance of MOF-based gas sensors relying on different transduction mechanisms, for example, chemiresistive, capacitive/impedimetric, field-effect transistor or Kelvin probe-based, mass-sensitive, and optical ones are comprehensively summarized. The latest progress for making large-area MOF films essential to the mass-production of relevant gas sensors is also included. The structural and compositional features of MOFs are intentionally correlated with the sensing performance. Challenges and opportunities for the further development and practical applications of MOF-based gas sensors are also given.

The structural diversity of highly connected metal–organic frameworks (MOFs) has long been limited due to the scarcity of highly connected metal clusters and the corresponding available topology. Herein, we deliberately chose a series of tritopic linkers with multiple substituents to construct a series of highly connected rare-earth (RE) MOFs. The steric hindrance of these substituents can be systematically tuned to generate various linker rotamers with tunable configurations and symmetries. For example, the methyl-functionalized linker (L-CH3) with C 2v symmetry exhibits larger steric hindrance, forcing two peripheral phenyl rings perpendicular to the central one. The combination of C 2v linkers and 9-connected RE6 clusters leads to the formation of a new fascinating (3,9)-c sep topology. Unlike Zr-MOFs exhibiting Zr6 clusters in various linker configurations and corresponding different structures, the adaptable RE6 clusters can undergo metal insertion and rearrange into new RE9 clusters when connected to an unfunctionalized linker (L–H) with C 1 symmetry, giving rise to a new (3,3,18)-c ytw topology. More interestingly, by judiciously combining the linkers with both small and bulky substituents through mixed-linker strategies, an RE9-based MOF with an engaging (3,3,12)-c flg topology could be obtained as a result of continuous steric hindrance control. In this case, the two mixed linkers adopt configurations with moderate steric hindrances. Molecular simulation demonstrates that the combination of substituents with various steric hindrances dictates the resulting MOF structures. This work provides insights into the discovery of unprecedented topologies through systematic and continuous steric tuning, which can further serve as a blueprint for the design and construction of highly complicated porous structures for sophisticated applications.

Three versatile amino-functionalized InIII/AlIII/ZrIV-MOFs with high-physicochemical stability for gas storage/separation, water purification and catalysis.

The separation of ethylene (C 2 H 4 )from amixture of ethane (C 2 H 6 ), ethylene (C 2 H 4 ), and acetylene (C 2 H 2 )a t normal temperature and pressure is as ignificant challenge. The sieving effect of pores is powerless due to the similar molecular size and kinetic diameter of these molecules.W e report an ew modification method based on as table ftw topological Zr-MOF platform (MOF-525). Introduction of acyclopentadiene cobalt functional group led to new ftw-type MOFs materials (UPC-612 and UPC-613), which increase the host-guest interaction and achieve efficient ethylene purification from the mixture of hydrocarbon gases.T he high performance of UPC-612 and UPC-613 for C 2 H 2 /C 2 H 4 / C 2 H 6 separation has been verified by gas sorption isotherms, density functional theory (DFT), and experimentally determined breakthrough curves.T his work provides ao ne-step separation of the ternary gas mixture and can further serve as ablueprint for the design and construction of function-oriented porous structures for such applications.

Acetylene (C 2 H 2) removal from ethylene (C 2 H 4) is a crucial step in the production of polymer-grade C 2 H 4 but remains a daunting challenge because of the similar physicochemical properties of C 2 H 2 and C 2 H 4. Currently energyintensive cryogenic distillation processes are used to separate the two gases industrially. A robust ultramicroporous metalorganic framework (MOF), Ni 3 (pzdc) 2 (7 Hade) 2 , is reported for efficient C 2 H 2 /C 2 H 4 separation. The MOF comprises hydrogen-bonded linked one-dimensional (1D) chains, and features high-density open metal sites (2.7 nm À3) and electronegative oxygen and nitrogen sites arranged on the pore surface as cooperative binding sites. Theoretical calculations, in situ powder X-ray diffraction and Fourier-transform infrared spectroscopy revealed a synergistic adsorption mechanism. The MOF possesses S-shaped 1D pore channels that efficiently trap trace C 2 H 2 at 0.01 bar with a high C 2 H 2 uptake of 60.6 cm 3 cm À3 and C 2 H 2 /C 2 H 4 selectivity.