Selective adsorption of SO2 is realized in a porous metal–organic framework material, and in‐depth structural and spectroscopic investigations using X‐rays, infrared, and neutrons define the underlying interactions that cause SO2 to bind more strongly than CO2 and N2.

Thermally-densified hafnium terephthalate UiO-66(Hf) is shown to exhibit the strongest isotropic negative thermal expansion (NTE) effect yet reported for a metal-organic framework (MOF). Incorporation of correlated vacancy defects within the framework affects both the extent of thermal densification and the magnitude of NTE observed in the densified product. We thus demonstrate that defect inclusion can be used to tune systematically the physical behaviour of a MOF.

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Understanding the molecular mechanism of proton conduction is crucial for the design of new materials with improved conductivity. Quasi-elastic neutron scattering (QENS) has been used to probe the mechanism of proton diffusion within a new phosphonate-based metal–organic framework (MOF) material, MFM-500(Ni). QENS suggests that the proton conductivity (4.5 × 10–4 S/cm at 98% relative humidity and 25 °C) of MFM-500(Ni) is mediated by intrinsic “free diffusion inside a sphere”, representing the first example of such a mechanism observed in MOFs.

MFM-300(Al) shows reversible uptake of NH (15.7 mmol g at 273 K and 1.0 bar) over 50 cycles with an exceptional packing density of 0.62 g cm at 293 K. In situ neutron powder diffraction and synchrotron FTIR micro-spectroscopy on ND @MFM-300(Al) confirms reversible H/D site exchange between the adsorbent and adsorbate, representing a new type of adsorption interaction.

Porous MFM-202a (MFM = Manchester Framework Material, replacing the NOTT designation) shows an exceptionally high uptake of acetylene, 18.3 mmol g −1 (47.6 wt %) at 195 K and 1.0 bar, representing the highest value reported to date for a framework material. However, at 293 K and 10 bar C 2 H 6 uptake (9.13 mmol g −1 ) is preferred. Dual-site Langmuir-Freundlich (DSLF)-and Numerical Integration (NI)-based IAST methods have been used to analyze selectivities for C 1 to C 3 hydrocarbons. MFM-202a exhibits broadly hysteretic desorption of acetylene; such behavior is important for practical gas storage since it allows the gas to be adsorbed at high pressure but stored at relatively low pressure. Stepwise uptake and hysteretic release were also observed for adsorption of other unsaturated light hydrocarbons (ethane and propene) in MFM-202a but not for saturated hydrocarbons (methane, ethane, and propane). MFM-202a has been studied by in situ synchrotron X-ray powder diffraction to reveal the possible phase transition of the framework host as a function of gas loading. A comprehensive analysis for the selectivities between these light hydrocarbons has been conducted using both IAST calculation and dual-component mixed-gas adsorption experiments, and excellent agreement between theory and experiment was achieved.

The adsorption of CO 2 on zeolite Li-Rho (unit cell composition Li 9.8 Al 9.8 Si 38.2 O 96 ) has been investigated by the measurement of adsorption isotherms (273 -300 K), breakthrough curves with a CO 2 /CH 4 /He mixture (308 K) and in situ synchrotron X-ray powder diffraction in CO 2 (298 K). The Rho framework distorts when in the Li-form to give a shape selective adsorbent for CO 2 over CH 4 , although breakthrough curves reveal diffusional limitations. In situ synchrotron powder XRD follows the expansion of the Li-Rho unit cell upon adsorption, which remains single phase to a CO 2 pressure of ca. 0.6 bar. Partial cation exchange of Li-2 Rho by Na + or Cs + gives two series of M,Li-Rho zeolites (M = Na, Cs). Where the occupancy of window sites (8R, D8R) between lta cages is less than 50%, hysteresis is not observed in CO 2 isotherms at 298 K. For Cs 1.8 Li 8 -Rho, which has a larger unit cell and a wider window than zeolite Li-Rho due to the presence of large Cs + cations in double 8-ring sites, breakthrough curves indicate faster CO 2 diffusion without significant loss of selectivity. We propose this control of adsorption kinetics of the flexible zeolite Rho via modification of cation content as a mechanism for cation controlled molecular sieving.

A nonporous square lattice (sql) coordination network [Co(bipy)2(NCS)2]n (sql-1-Co-NCS) exhibits recyclable switching induced by CO2. The sorption isotherms are stepped with moderate hysteresis, temperature controlled and saturation uptake is fixed. Such switching, which has rarely been observed, offers the promise of exceptional working capacity for gas storage.