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MFM‐520(Zn) confines dimers of NO2 with a high adsorption of 4.52 mmol g−1 at 1 bar at 298 K. The synthesis and the incommensurate structure of Cu‐doped MFM‐520(Zn) are reported. The introduction of paramagnetic Cu2+ sites allows investigation of the electronic and geometric structure of metal site by in situ electron paramagnetic resonance (EPR) spectroscopy upon adsorption of NO2. By combining continuous wave and electron‐nuclear double resonance spectroscopy, an unusual reverse Berry distorted coordination geometry of the Cu2+ centers is observed. Interestingly, Cu‐doped MFM‐520(Zn0.95Cu0.05) shows enhanced adsorption of NO2 of 5.02 mmol g−1 at 1 bar at 298 K. Whereas MFM‐520(Zn) confines adsorbed NO2 as N2O4, the presence of monomeric NO2 at low temperature suggests that doping with Cu2+ centers into the framework plays an important role in tuning the dimerization of NO2 molecules in the pore via the formation of specific host‐guest interactions. [ABSTRACT FROM AUTHOR]

The interactions between adsorbed gas molecules within porous metal-organic frameworks are crucial to gas selectivity but remain poorly explored. Here, we report the modulation of packing geometries of CO2 and C2H2 clusters within the ultramicroporous CUK-1 material as a function of temperature. In-situ synchrotron X-ray diffraction reveals a unique temperature-dependent reversal of CO2 and C2H2 adsorption affinities on CUK-1, which is validated by gas sorption and dynamic breakthrough experiments, affording high-purity C2H2 (99.95%) from the equimolar mixture of C2H2/CO2 via a one-step purification process. At low temperatures (<253 K), CUK-1 preferentially adsorbs CO2 with both high selectivity (>10) and capacity (170 cm3 g−1) owing to the formation of CO2 tetramers that simultaneously maximize the guest-guest and host-guest interactions. At room temperature, conventionally selective adsorption of C2H2 is observed. The selectivity reversal, structural robustness, and facile regeneration of CUK-1 suggest its potential for producing high-purity C2H2 by temperature-swing sorption. Guest clusters within confined nanospaces have a significant impact on molecular recognition. Here authors highlight the potential to systematically control gas-cluster rearrangement, leading to tunable sorption and separation behaviour in a MOF. [ABSTRACT FROM AUTHOR]

Since its first industrial production in 1890s, acetylene has played a vital role in manufacturing a wide spectrum of materials. Although current methods and infrastructures for various segments of acetylene industries are well‐established, with emerging functional porous materials that enabled desired selectivity toward target molecules, it is of timely interest to develop new efficient technologies to promote safer acetylene processes with a higher energy efficiency and lower carbon footprint. In this Minireview, we, from the perspective of materials chemistry, review state‐of‐the‐art examples of advanced porous materials, namely metal–organic frameworks and decorated zeolites, that have been applied to the purification and storage of acetylene. We also discuss the challenges on the roadmap of translational research in the development of new solid sorbent‐based separation technologies and highlight areas which require future research efforts. [ABSTRACT FROM AUTHOR]

We report reversible high capacity adsorption of SO2 in robust Zr‐based metal–organic framework (MOF) materials. Zr‐bptc (H4bptc=biphenyl‐3,3′,5,5′‐tetracarboxylic acid) shows a high SO2 uptake of 6.2 mmol g−1 at 0.1 bar and 298 K, reflecting excellent capture capability and removal of SO2 at low concentration (2500 ppm). Dynamic breakthrough experiments confirm that the introduction of amine, atomically‐dispersed CuII or heteroatomic sulphur sites into the pores enhance the capture of SO2 at low concentrations. The captured SO2 can be converted quantitatively to a pharmaceutical intermediate, aryl N‐aminosulfonamide, thus converting waste to chemical values. In situ X‐ray diffraction, infrared micro‐spectroscopy and inelastic neutron scattering enable the visualisation of the binding domains of adsorbed SO2 molecules and host–guest binding dynamics in these materials at the atomic level. Refinement of the pore environment plays a critical role in designing efficient sorbent materials. [ABSTRACT FROM AUTHOR]

Nuclear power will continue to provide energy for the foreseeable future, but it can pose significant challenges in terms of the disposal of waste and potential release of untreated radioactive substances. Iodine is a volatile product from uranium fission and is particularly problematic due to its solubility. Different isotopes of iodine present different issues for people and the environment. 129I has an extremely long half-life of 1.57 × 107 years and poses a long-term environmental risk due to bioaccumulation. In contrast, 131I has a shorter half-life of 8.02 days and poses a significant risk to human health. There is, therefore, an urgent need to develop secure, efficient and economic stores to capture and sequester ionic and neutral iodine residues. Metal–organic framework (MOF) materials are a new generation of solid sorbents that have wide potential applicability for gas adsorption and substrate binding, and recently there is emerging research on their use for the selective adsorptive removal of iodine. Herein, we review the state-of-the-art performance of MOFs for iodine adsorption and their host–guest chemistry. Various aspects are discussed, including establishing structure–property relationships between the functionality of the MOF host and iodine binding. The techniques and methodologies used for the characterisation of iodine adsorption and of iodine-loaded MOFs are also discussed together with strategies for designing new MOFs that show improved performance for iodine adsorption. [ABSTRACT FROM AUTHOR]

Understanding the mechanism of assembly and function of metal-organic frameworks (MOFs) is important for the development of practical materials. Herein, we report a time-resolved diffraction analysis of the kinetics of formation of a robust MOF, MFM-300(Fe), which shows high adsorption capacity for CO2 (9.55 mmol g−1 at 293 K and 20 bar). Applying the Avrami-Erofe'ev and the two-step kinetic Finke-Watzky models to in situ high-energy synchrotron X-ray powder diffraction data obtained during the synthesis of MFM-300(Fe) enables determination of the overall activation energy of formation (50.9 kJ mol−1), the average energy of nucleation (56.7 kJ mol−1), and the average energy of autocatalytic growth (50.7 kJ mol−1). The synthesis of MFM-300(Fe) has been scaled up 1000-fold, enabling the successful breakthrough separations of the CO2/N2 mixture in a packed-bed with a selectivity for CO2/N2 of 21.6. This study gives an overall understanding for the intrinsic behaviors of this MOF system, and we have determined directly the binding domains and dynamics for adsorbed CO2 molecules within the pores of MFM-300(Fe). [ABSTRACT FROM AUTHOR]

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The microporous metal–organic framework {[Zn2(L)]·(H2O)3}∞ (H4L = 1,2,4,5-tetrakis(4-carboxyphenyl)benzene) has been synthesised using near-critical water (300 °C) as a cleaner alternative to toxic organic solvents. A single crystal X-ray structure determination confirms that the complex incorporates tetrahedral Zn(ii) centres bridged through the carboxylate anions to form a binuclear building block, which extends into a one dimensional chain along the c axis. Four L4− ligands bind to each Zn(ii) centre and cross-link the one dimensional chains along both a and b axes to afford a three dimensional network structure incorporating pores of ca. 4.3 Å in diameter. The complex shows high thermal stability up to 425 °C by gravimetric thermal analysis, and on desolvation, displays a high adsorption enthalpy of 11.0 kJ mol−1 for H2 uptake at zero coverage, consistent with the narrow pore diameter for the framework. [ABSTRACT FROM AUTHOR]