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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 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]

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]

Comprehensive Summary: The sequestration of organic luminescent molecules (OLMs) within cage‐based metal‐organic frameworks (MOFs) as a dispersion platform has been developed to impede aggregation‐caused quenching (ACQ). The homogenous encapsulation of distinct luminescent guests of different sizes and emissive behaviors in the cage structure of a MOF resulted in high fluorescent quantum yields of 44.8% for DAPI@NKU‐110 (DAPI = 4',6‐diamidino‐2‐phenylindole), 65.4% for TPPA@NKU‐110 (TPPA = tris(4‐(pyridin‐4‐ yl)phenyl)amine), 31.3% for R6G@NKU‐110 (R6G = Rhodamine 6G), and 58.3% for PY@NKU‐110 (PY = Pyronin Y), attributable to the confinement effect caused by the rigid cages of NKU‐110. More significantly, a positive correlation of the encapsulated quantity of OLMs with their concentration in the in‐situ solvothermal reaction was unveiled by spectral analysis and utilized to facilely fabricate a white‐light‐emitting crystal material TPPA+R6G@NKU‐110. This material features a large crystal size on the millimeter‐scale, broadband white emission, ideal CIE coordinates (0.33, 0.34), and a high quantum yield (49.1%) when excited at 365 nm. Moreover, such a strategy can be easily generalized to an abundance of other cage‐based MOFs and a plentiful volume of OLMs for the future development of colorful, high performance luminescent materials. [ABSTRACT FROM AUTHOR]

Two luminescent coordination polymers (CPs), {[Cd2L2(H2O)4]·H2O}n (1) and {[Zn2L2(H2O)4]·H2O}n (2) (H2L = 5-(1H-1,2,4-triazol-1-yl)isophthalic acid) are reported herein. The CPs reveal readily dispersible two-dimensional (2D) layer structures with considerable stability in aqueous media within a wide pH range (pH = 2–12). Sensing experiments indicate that they can serve as highly selective and sensitive fluorescent probes toward CrVI-anions (CrO42− and Cr2O72−). [ABSTRACT FROM AUTHOR]

Abstract: A new luminescent ZnII‐MOF with 1D triangular channels along the b axis, namely NUM‐5, has been successfully assembled and well characterized, which features good stability, especially in aqueous solution. Interestingly, this compound exhibits a fast, sensitive and selective luminescence quenching response towards CrVI (Cr2O72−/CrO42−) in aqueous solution. The detection limits towards Cr2O72− and CrO42− ions are estimated to be 0.7 and 0.3 ppm, respectively, which are among the lowest detection limits reported for the MOF‐based fluorescent probes that can simultaneously detect Cr2O72− and CrO42− in aqueous environment. The possible detection mechanism has been discussed in detail. Moreover, it can be easily regenerated after detection experiments, indicative of excellent recyclability. All these results suggest NUM‐5 to be a highly selective and recyclable luminescent sensing material for the quantitative detection of CrVI anions in aqueous solution. [ABSTRACT FROM AUTHOR]

In this work, the single crystal to single crystal (SCSC) transformations in three mononuclear copper complexes [Cu L 2 2 ]Cl 2 ·2H 2 O ( 1 ), [Cu L 1 2 Cl 2 ] ( 2 ), and [Cu L 2 2 ]Cl 2 ·4H 2 O ( 3 ) ( L 1 = di-2-pyridyl ketone, L 2 = di(pyridin-2-yl)methanediol) are realized by the irreversible dehydration and hydration reaction of L 1 and L 2 . Dark purple crystal 1 is obtained by self-assembly of L 1 and CuCl 2 ·2H 2 O in solvothermal reactions, in which the carbonyl group of L 1 undergoes a hydration addition reaction to form L 2 . On heating, 1 transforms to 2 by dehydrating water accompanied by the change of the color and coordination octahedron of Cu II ions. In a saturated water vapor environment, 2 can absorb six water molecules and transform to 3 with the same color and coordination environment with 1 but different lattice water. The SCSC process from 2 to 3 is reversible: 3 can transform back to 2 on heating like that of 1 . Chroma rewritable behaviors in the structural transformation of the complexes make them visually identifiable temperature or water probes.

As a kind of MOFs, cage-based MOFs usually carry large voids and small windows, which are advantageous to the storage of small molecules that remain kinetically trapped inside the cages (confinement effect). By adjusting the size of windows via reticular synthesis, the cage-based MOFs can selectively capture and separate the suitable size molecules. Here, considering angle-directed and face-directed strategies, a novel multicage-based MOF NUM-3 with a new (3,4,5)-connected topology was successfully constructed in the mixed-ligands assembly. In the framework of NUM-3, there exist four different kinds of cages, which exhibit diverse polyhedral configurations. The four kinds of cages in the order ABCDDCBA as the minimum repeat unit form a 1D tortuous channel along the c axis. Based on the structure characteristics that the 1D channel exhibits different inner diameter (from 4.0 to13.0 Å), NUM-3a (actived NUM-3) can capture CO 2 over C 2 H 4 and C 2 H 6 by the size selectivity (the empirical kinetic diameters: CO 2 < C 2 H 4 < C 2 H 6 ). In addition, it also exhibits commendable selectivity for CO 2 over N 2 and CH 4 .