Vapor-assisted synthesis of the MOF-74 metal-organic framework family from zinc, cobalt, and magnesium oxides

In this work, we investigate the vapor-assisted synthesis of the metal-organic framework MOF-74 starting from three metal oxides (ZnO, CoO, and MgO). Depending on the nature of the added vapor (H2O, DMF, DMSO), the metal oxide, and the temperature, the outcome of the reaction can be directed towards the desired porous phase. Ex situ and in situ XRD measurements reveal the formation of an intermediate phase during the reaction of MgO with H4dobdc, while the MOF-74 phase forms directly for ZnO and CoO. The reduced CO2 uptake of the resulting materials compared to solvothermally prepared MOFs might be offset by the convenience of the presented route and the promise of a high space time yield.

Pressure-induced inclusion of neon in the crystal structure of a molecular Cu2(pacman) complex at 4.67 GPa

Crystals of Cu₂(pacman) inflate on taking up neon at 46 000 atm through a switch in the ligand conformation.

Fast screening of porous materials for noble gas adsorption and separation: a classical density functional approach

The design and screening of porous materials for noble gas adsorption and separation are an important issue in the production and utilization of gases. The conventional method to do this is via molecular simulation. In this work, we introduced a classical density functional theory (CDFT) to replace molecular simulation because CDFT is more efficient. A molecular dynamics (MD)/CDFT combined method was proposed to consider the flexibility of the adsorbent. The theory was first examined by comparing it to reported experiments and simulations. Then, the theory was applied to determine the most favorable adsorbents for noble gas adsorption/separation from 4764 real adsorbents and 1200 hypothetical adsorbents. A series of favorable adsorbents was identified, and some of them seemed promising. The macroscopic adsorption isotherms and microscopic density profiles of the most favorable adsorbents were examined, and the adsorption mechanisms were revealed. The specific separation of Kr/Xe was examined, and two of the adsorbents showed higher adsorption efficiency than shown in previously reported data.

Neon-Bearing Ammonium Metal Formates: Formation and Behaviour under Pressure

The incorporation of noble gas atoms, in particular neon, into the pores of network structures is very challenging due to the weak interactions they experience with the network solid. Using high-pressure single-crystal X-ray diffraction, we demonstrate that neon atoms enter into the extended network of ammonium metal formates, thus forming compounds Ne_x [NH₄ ][M(HCOO)₃ ]. This phenomenon modifies the compressional and structural behaviours of the ammonium metal formates under pressure. The neon atoms can be clearly localised within the centre of [M(HCOO)₃ ]₅ cages and the total saturation of this site is achieved after ∼1.5 GPa. We find that by using argon as the pressure-transmitting medium, the inclusion inside [NH₄ ][M(HCOO)₃ ] is inhibited due to the larger size of the argon. This study illustrates the size selectivity of [NH₄ ][M(HCOO)₃ ] compounds between neon and argon insertion under pressure, and the effect of inclusion on the high-pressure behaviour of neon-bearing ammonium metal formates.