Zirconium-Based Metal Organic Frameworks for the Capture of Carbon Dioxide and Ethanol Vapour. A Comparative Study.

This paper reports on the comparison of three zirconium-based metal organic frameworks (MOFs) for the capture of carbon dioxide and ethanol vapour at ambient conditions. In terms of efficiency, two parameters were evaluated by experimental and modeling means, namely the nature of the ligands and the size of the cavities. We demonstrated that amongst three Zr-based MOFs, MIP-202 has the highest affinity for CO2 (-50 kJ·mol-1 at low coverage against around -20 kJ·mol-1 for MOF-801 and Muc Zr MOF), which could be related to the presence of amino functions borne by its aspartic acid ligands as well as the presence of extra-framework anions. On the other side, regardless of the ligand size, these three materials were able to adsorb similar amounts of carbon dioxide at 1 atm (between 2 and 2.5 µmol·m-2 at 298 K). These experimental findings were consistent with modeling studies, despite chemisorption effects, which could not be taken into consideration by classical Monte Carlo simulations. Ethanol adsorption confirmed these results, higher enthalpies being found at low coverage for the three materials because of stronger van der Waals interactions. Two distinct sorption processes were proposed in the case of MIP-202 to explain the shape of the enthalpic profiles.

Sonochemical synthesis and crystal structure of di-methyl-ammonium bis-[3-carb-oxy-2-(di-methyl-amino)-propano-ato-κ2 N,O 1]chlorido-chromium(II) monohydrate.

The title complex, [(CH3)2NH2][Cr(C6H10NO4)2Cl]·H2O, was synthesized sonochemically. The complex anion consists of a chromium(II) ion ligated by two 3-carb-oxy-2-(di-methyl-amino)-propano-ate anions. They coordinate in a bidentate manner, with a carboxyl-ate oxygen atom and the nitro-gen atom cis to each other in the equatorial plane, while the apical position is occupied by a Cl- ion. Hence, the chromium(II) ion is five-coordinate with a quasi-ideal square-pyramidal geometry; τ5 parameter = 0.01. The complex crystallizes as a monohydrate and in the crystal, the water mol-ecule and the di-methyl-ammonium counter-ion link the complex cations via N-H⋯O, N-H⋯Cl, Owater-H⋯O, O-H⋯Owater and O-H⋯O hydrogen bonds, forming a supra-molecular framework. There are also a number of C-H⋯O hydrogen bonds present that reinforce the framework structure. The crystal studied was refined as a racemic twin.

Electrically Induced Breathing of the MIL-53(Cr) Metal-Organic Framework.

The breathing behavior of the MIL-53(Cr) metal-organic framework (MOF) has been explored previously upon guest-adsorption and thermal and mechanical stimuli. Here, advanced molecular simulations based on the use of an accurate force field to describe the flexibility of this porous framework demonstrate that the application of an electrical field induces the structural switching of this MOF leading to a first-order transition and a volume change of more than 40%. This motivated us to electrically tune the pore size of MIL-53(Cr) with the idea to propose a new concept to selectively capture CO2 over CH4 via a molecular sieving that paves the way toward the optimization of current separation-based processes.

Synthesis and crystal structure of ((E)-{2-[(E)-(4-hy-droxynaphthalen-1-yl)methyl-idene]hydrazin-1-yl}(methyl-sulfan-yl)methyl-idene)azanium hydrogen sulfate monohydrate.

In the title hydrated mol-ecular salt, C13H14N3S+·HSO4-·H2O, the protonation of the azomethine N atom in sulfuric acid medium involves the formation of the bis-ulfate anion. The mol-ecular structure of the cation is obtained from the thiol tautomer of thio-semicarbazone wherein the naphthalene moiety and the conjugation of the bonds contribute to the planarity of the mol-ecular skeleton. In the crystal, the cation, anion and water mol-ecule of crystallization are linked by a series of O-H⋯O and N-H⋯O hydrogen bonds, forming a three-dimensional network. Within this network, there are also C-H⋯π inter-actions present involving symmetry-related naphthalene rings.

Crystal structure of 2-(1H-imidazol-3-ium-4-yl)ethanaminium dichloride, a re-determination.

The crystal structure of the title mol-ecular salt, C5H11N3 (+)·2Cl(-), was redetermined. In comparison with the previous study [Bonnet et al. (1975 ▸). Bull. Soc. Fr. Mineral. Crist. 98, 208-213.], the positions of some H atoms were corrected, allowing a more accurate description of the hydrogen-bonding scheme. In addition, the absolute structure was also determined. The maximum differences in terms of bond lengths and angles between the two determinations are 0.022 Šand 1.43°, respectively. The organic cation display a anti conformation of the protonated amine function and the imidazolium ring. The dihedral angle between the imidazolium plane and the plane through the C-C-N side chain is 29.58 (3)°. In the crystal, the organic cations and Cl(-) anions are stacked alternatively into layers parallel to (100). N-H⋯Cl hydrogen bonds between all H atoms of the ammonium group and both N-H groups of the imidazolium ring and the Cl(-) acceptor anions lead to the linkage of organic and inorganic layers into a three-dimensional network.

Crystal structure of 2-(1H-imidazol-4-yl)ethanaminium chloride.

The title mol-ecular salt, C5H10N3 (+)·Cl(-), was obtained as by-product in the attempted synthesis of a histamine derivative. The terminal amino group of the starting material is protonated. The Cimidazole-C-C-N(H3)(+) group in the cation is in an anti conformation with a torsion angle of 176.22 (10)°. In the crystal, cations and anions are linked via N-H⋯N and N-H-Cl hydrogen bonds, forming a two-dimensional network parallel to (10-1). A single weak C-H⋯Cl hydrogen bond completes a three-dimensional network.

(E)-2-[(1H-Imidazol-4-yl)methyl-idene]hydrazinecarbo-thio-amide monohydrate.

In the title compound, C5H7N5S·H2O, the main mol-ecule is approximately planar, with a maximum deviation from the mean plane through the non-H atoms of 0.1478 (12) Šfor the amine N atom. In the crystal, the components are connected via N-H⋯O, N-H⋯S and O-H⋯N hydrogen bonds, forming a three-dimensional network.