Here, a Y­(III)-based metal–organic framework, JLU-MOF112 {[Y3(μ3-O)2(μ3-OH)­(H2O)2(BTCTBA)2]·2­[(CH3)2NH2]·5DMF·C6H5Cl·4H2O}, has been successfully synthesized under solvothermal conditions. JLU-MOF112 was constructed with amide-functionalized tricarboxylate ligands and Y­(III)-based infinite chains, where the Y3 repeating units are arranged in a trans order. The overall framework could be viewed as a novel (3,5)-connected net with two types of channels along the [100] and [010] directions. JLU-MOF112 possesses a large BET surface area (1553 m2 g–1), a permanent pore volume (0.67 cm3 g–1), and outstanding thermal and chemical stability, which give JLU-MOF112 potential for the purification of natural gas, especially the equimolar separation of C3H8/CH4 with a high selectivity of 176. In addition, benefiting from the amide functional groups as Brønsted basic sites and the exposure of open metal sites as Lewis acid sites after activation, JLU-MOF112 can serve as a high-efficiency heterogeneous catalyst for Knoevenagel condensation by the reactions of malononitrile with benzaldehyde (yield of 98%, turnover number of 392, and turnover frequency of 3.27 min–1) and diverse aldehyde compounds. A rational mechanism was put forward that the Knoevenagel condensation was catalyzed by the synergistic effect of the Lewis acid sites and Brønsted basic sites, engendering the polarization of the carbonyl groups and the deprotonation of the methylene groups for nucleophilic attack.

Distinct from predominately known fluorescence quenching (turn-off) detection, turn-on response to hazardous substances by luminescent metal−organic frameworks (LMOFs) could greatly avoid signal loss and susceptibility to environmental stimulus. However, such detection rarely occurs and lacks theoretical elucidations. Here, we present the first example of unique turn-on and unprecedented turn-off−on responses to a variety of acids by a stable 12-connected hexanuclear Y(III)cluster-based LMOF material�JLU-MOF111, featuring the nondefault pcu topology. Benefiting from the "pocket" structures formed by the carbazole-containing ligands, JLU-MOF111 can sense multiple inorganic and organic acids via different degrees of fluorescence turn-on behaviors. Particularly, turn-on sensing of HNO 3 , HCl, HBr, and TFA is hypersensitive with LODs as low as the ppb level. Theoretical calculations confirm weak interactions in acid−ligand complexes, which lead to constrained rotations of benzene moieties of the ligands when the complexes decay from excited states. These account for the turn-on response through reduced nonradiative energy consumption that competes with emissive decay. The turn-off−on response to 4-NBA and 3,5-DNBA involves an excited-state electron transfer process that dominates the turn-off stage and prohibited nonradiative decay that competes with the intrinsic emission of the ligand and dominates the turn-on stage. This work has a guiding significance for the full-scale understanding of turn-on and turn-off−on sensing performance in LMOF materials and beyond.

Herein, by using pillaring ligands with different lengths, two copper-based metal-organic frameworks, compounds 1 (Cu2(bada)2(dabco)) and 2 (Cu2(bada)2(bipy)) (bada = 4,4’-carbonylbis(azanediyl)di-benzoic acid, dabco = 1,4-diazabicyclo[2.2.2]octane, bipy = 4,4’-bipyridine) with urea-functionalized...

On the basis of different V-shaped ligands, three zirconium−organic frameworks (JLU-Liu45, Zr-SDBA, and Zr-OBBA) have been successfully constructed. By regulating spatial configuration and functional groups of organic ligands, these assynthesized Zr-MOFs (MOF = metal−organic framework) display distinct structures and different light hydrocarbon adsorption/ separation capabilities. JLU-Liu45, with a double-walled interpenetrated 3D primitive cubic (pcu) framework, exhibits good gasadsorption capacity but not prominent selective separation ability. Through regulating sizes and torsion angles of the organic ligands, Zr-SDBA possesses a 2D square lattice (sql) network, while Zr-OBBA displays a non-interpenetrated 3D pcu framework. Furthermore, by regulating functional groups on the ligands, Zr-SDBA shows prominent C 2 H 2 uptake (101.2 cm 3 •g −1 ) and the best C 2 H 2 /CH 4 selectivity (230.5, 1:1) among the three Zr-MOFs, and Zr-OBBA shows a significant C 3 H 8 /CH 4 selectivity (105.6, 1:1). This work demonstrates the feasibility of structural regulation for MOF materials in the light hydrocarbon adsorption/separation field.

Metal‒organic frameworks (MOFs) have shown great potential in catalytic fields, especially zeroing in on environmental issues by chemical fixations of hazardous gases towards value-added products. Despite that, difficulties in in-situ...

Herein, a novel luminescent Zn-LMOF, JLU-MOF109 ([Zn(PBBA)(H2O)]·3DMF·2H2O, PBBA = 4,4′-(2,6-pyrazinediyl)bis[benzoic acid], DMF = N,N-dimethylformamide), was successfully synthesized under solvothermal conditions. Zinc ions are connected by PBBA ligands to form two-dimensional (2D) layers, and the layers are further propped up through hydrogen-bonding interactions. JLU-MOF109 exhibits good sensitivity to inorganic pollutants, Fe3+ and Cr2O7 2–, as well as nitro aromatic explosives, 2,4,6-trinitrophenol and 2,4-dinitrophenol. JLU-MOF109 exhibits high K sv (at 104 M–1 level) and low limit of detection values (∼10–6 mol/L) for the abovementioned hazardous pollutants, which is better than a majority of previously reported MOF-based fluorescent sensors. With good stability in the aqueous phase, JLU-MOF109 can serve as a promising chemical sensor for pollutant detection in wastewater.

Enteric methane (CH 4) emissions in ruminants have attracted considerable attention due to their impact on greenhouse gases and the contribution of agricultural practices to global warming. Over the last two decades, a number of approaches have been adopted to mitigate CH 4 emissions. However, the mechanisms of methanogenesis have still not been fully defined. According to the genome sequences of M. ruminantium in the rumen and of M. AbM4 in the abomasum, the pathways of carbon dioxide (CO 2) reduction and formate oxidation to CH 4 have now been authenticated in ruminants. Furthermore, in the light of species or genera description of methanogens, the precursors of methanogenesis discovered in the rumen and research advances in related subjects, pathways of acetate dissimilation via Methanosarcina and Methanosaeta as well as metabolism of methanol to CH 4 might be present in the rumen, although neither process has yet been experimentally demonstrated in the rumen. Herein the research advances in methanogenesic mechanisms including existing and potential mechanisms are reviewed in detail. In addition, further research efforts to understand the methanogenesis mechanism should focus on isolation and identification of more specific methanogens, and their genome sequences. Such increased knowledge will provide benefits in terms of improved dietary energy utilization and a reduced contribution of enteric CH 4 emissions to total global greenhouse gas emissions from the ruminant production system.

No abstract