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The development of adsorption-based separation processes alternative to the energy-intensive cryogenic distillation for a mixture of propylene and propane remains essential but challenging in gas industries. Molecular sieving separation of C

Multifunctional metal-organic frameworks (MOFs) that possess permanent porosity are promising catalysts in organic transformation. Herein, we report the construction of a hierarchical MOF functionalized with basic aliphatic amine groups and polyvinylpyrrolidone-capped platinum nanoparticles (Pt NPs). The postsynthetic covalent modification of organic ligands increases basic site density in the MOF and simultaneously introduces mesopores to create a hierarchically porous structure. The multifunctional MOF is capable of catalyzing a sequential Knoevenagel condensation-hydrogenation-intramolecular cyclization reaction. The unique selective reduction of the nitro group to intermediate hydroxylamine by Pt NPs supported on MOF followed by intramolecular cyclization with a cyano group affords an excellent yield (up to 92%) to the uncommon quinoline N-oxides over quinolines. The hierarchical MOF and polyvinylpyrrolidone capping agent on Pt NPs synergistically facilitate the enrichment of substrates and thus lead to high activity in the reduction-intramolecular cyclization reaction. The bioactivity assay indicates that the synthesized quinoline N-oxides evidently inhibit the proliferation of lung cancer cells. Our findings demonstrate the feasibility of MOF-catalyzed direct synthesis of bioactive molecules from readily available compounds under mild conditions.

The pore size of adsorbents plays a vital role in determining the overall separation performance of gas separation and purification by adsorption. In this work, the pore apertures of the coordination pillared layer (CPL) was systematically controlled by adjusting the length of pillared ligands. We used pyrazine, 4,4'-bipyridine, and 1,2-di(4-pyridyl)-ethylene with increased length to synthesize CPL-1 (L = pyrazine), CPL-2 (L = 4,4'-bipyridine), and CPL-5 [L = 1,2-di(4-pyridyl)-ethylene], respectively. The aperture size of these CPLs varies from 4 to 11 A: CPL-1 (4 × 6 A2), CPL-2 (9 × 6 A2), and CPL-5 (11 × 6 A2). Among the three frameworks, CPL-2 exhibits the highest C2H2 uptake at ambient conditions as it has moderate pore size and porosity. However, CPL-1 has the best separation performance in the breakthrough experiments with binary gas mixture of C2H2/C2H4, thanks to the optimal pore size nearly excluding C2H4, which is only observed in the state-of-the-art UTSA-300a so far. The DFT calculations were carried out to elucidate the specific adsorption sites for both acetylene and ethylene among these frameworks. The modeling results suggest that binding strength is highly related to aperture size and that CPL-1 shows the highest adsorption selectivity owing to the optimal pore size. This work demonstrates that engineering pore size enables us to fabricate the highly efficient metal-organic framework (MOF)-based adsorbents for specific gas separation on the basis of the isoreticular chemistry.

The demand for CO2/C2H2 separation, especially the removal of CO2 impurity, continues to grow because of the high-purity C2H2 required for various industrial applications. The adsorption separation of C2H2 and CO2 via porous materials is gaining a considerable attention as it is more energy-efficient compared with cryogenic distillation. The ideal porous materials are those that preferentially adsorb CO2 over C2H2; however, very few adsorbents meet such requirement. Herein, two isostructural cyclodextrin-based CD-MOFs (CD-MOF-1 and CD-MOF-2) were demonstrated to have an inverse ability to selectively capture CO2 from C2H2 by single-component adsorption isotherms and dynamic breakthrough experiments. These two MOFs showed excellent adsorption capacity and benchmark selectivity (118.7) for CO2/C2H2 mixture at room temperature, enabling the pure C2H2 to be obtained in only one step. This work revealed that these materials were promising adsorbents for obtaining high-purity C2H2 via selectively capturing CO2 ...

The separation of carbon dioxide (CO2) from hydrocarbons is a critical process for the production of clean energy and high-purity chemicals. Adsorption based on molecular sieving is an energy-saving separation process; however, most of molecular sieves with narrow and straight pore channels exhibit low CO2 uptake capacity. Here, we report that a twofold interpenetrated copper coordination network with a consecutive pocket-like pore structure, namely, SIFSIX-14-Cu-i (SIFSIX = hexafluorosilicate, 14 = 4,4′-azopyridine, i = interpenetrated) is a remarkable CO2/CH4 molecular sieving adsorbent which completely blocks the larger CH4 molecule with unprecedented selectivity, whereas it has excellent CO2 uptake (172.7 cm3/cm3) under the ambient condition. The exceptional separation performance of SIFSIX-14-Cu-i is attributed to its unique pore shape and functional pore surface, which combine a contracted pore window (3.4 A) and a relatively large pore cavity decorated with high density of inorganic anions. Dispers...

Mimicking a biocatalytic system has been one of the prevalent strategies for the design of novel and efficient chemical transformations. Among the enzyme-catalyzed reactions, the cooperative interplay of Lewis- and Bronsted-acidic functionalities at active sites represents a common feature in activating reactants. Employing MIL-101(Cr) as a biomimetic platform, we customize a sulfonic group (SO3H) into its hierarchical pores to generate a heterogeneous catalyst for transfer hydrogenation of imines by using Hantzsch ester as the reductant. Both aldimines and ketimines were efficiently converted to their hydrogenated counterparts in a manner similar to metal enzymes. The Cr3+ node and sulfonic acid functionality encapsulated in MOF cages worked cooperatively in promoting this transformation, resulting in an enhanced reactivity as compared to its homogeneous analogue. Furthermore, MIL-101(Cr)-SO3H could be recycled for many times without considerable loss in reactivity.