Institut Lavoisier (UMR CNRS 8180), Institut Universitaire de France, Porous Solids Group, Tectospin, Université de Versailles Saint Quentin en Yvelines, 45, avenue des Etats-Unis, 78035 Versailles, France.
A new aluminum trimesate Al12O(OH)18(H2O)3(Al2(OH)4)[btc]6.24H2O, denominated MIL-96, was synthesized under mild hydrothermal conditions (210 degrees C, 24 h) in the presence of 1,3,5-benzenetricarboxylic acid (trimesic acid or H3btc) in water. Hexagonal crystals, allowing a single-crystal XRD analysis, are grown from a mixture of trimethyl 1,3,5-benzenetricarboxylate (Me3btc), HF, and TEOS. The MIL-96 structure exhibits a three-dimensional (3D) framework containing isolated trinuclear mu3-oxo-bridged aluminum clusters and infinite chains of AlO4(OH)2 and AlO2(OH)4 octahedra forming a honeycomb lattice based on 18-membered rings. The two types of aluminum groups are connected to each other through the trimesate species, which induce corrugated chains of aluminum octahedra, linked via mu2-hydroxo bonds with the specific -cis-cis-trans- sequence. The 3D framework of MIL-96 reveals three types of cages. Two of them, centered at the special positions 0 0 0 and 2/3 1/3 1/4, have estimated pore volumes of 417 and 635 A3, respectively, and encapsulate free water molecules. The third one has a smaller pore volume and contains disordered aluminum octahedral species (Al(OH)6). The solid-state NMR characterization is consistent with crystal structure and elemental and thermal analyses. The four aluminum crystallographic sites are resolved by means of 27Al 3QMAS technique. This product is able to sorb both carbon dioxide and methane at room temperature (4.4 mmol.g(-1) for CO2 and 1.95 mmol.g(-1) for CH4 at 10 bar) and hydrogen at 77 K (1.91 wt % under 3 bar).
"be desorbed under flowing air . This assumption is also in agreement with thermo gravimetric measurement (TGA) performed by Loiseau et al. and Yaghi et al.   reporting that water molecules are adsorbed on the surface of MOF as well as on the positively charged metal sites inside and can be reversible removed upon heating without influencing the MOF structure leaving unsaturated metal sites unoccupied and available for other guest molecules. Moreover according to Yaghi et al.  the adsorption of molecules into MOFs with unsaturated metal sites depends not only on the size and shape of the guest molecules but also on their electronic affinity for the metal site. "
[Show abstract][Hide abstract] ABSTRACT: Metalorganic frameworks (MOFs) are porous crystalline materials that can be synthesized using various metal ions and organic linkers. Due to their great physical, chemical, and geometrical variety, MOFs are very attractive for the potential application as selective gas sensing materials. The selectivity and sensitivity towards target gases is affected by chemical and/or geometrical properties of sensing layers. In this study we examine work function based gas sensing properties of MOFs, consisting of the same organic linker, benzene tricarboxylate (BTC), and different metal sites (Co, Ni, Cd, Al), towards different linear alkanes and monohydric alcohols at room temperature. The influence of oxygen and humidity on the gas sensing performances as well as the possible reaction mechanism are discussed. It was shown that exposure to alcohol leads to strong and concentration dependent changes in work function that increase with increasing length of the carbon chain of the alcohol while alkanes with similar carbon chains can hardly be detected. Moreover, the type of the metal site does not affect sensing of alcohols and alkanes qualitatively. By analysing the influence of size and polarity of the target gases, we assume that adsorption mechanisms and adsorption sites on BTC–MOF for polar and nonpolar molecules are different.
Sensors and Actuators B Chemical 12/2013; 193:911-917. DOI:10.1016/j.snb.2013.11.102 · 4.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gas sorption is a key technology for solving the global issues of energy and the environment that beset the world. From the
end of the twentieth century, porous coordination polymers have been synthesized and studied as candidates for advanced adsorbents
with a wide variety of applications. The regular nanospace of porous coordination polymers shows unique gas molecule capture
and creates a new chemistry in the field of porous materials. In this article, we focus on the gas sorption properties of
porous coordination polymers. Their uniqueness is illustrated using current representative results and discussed together
with perspectives on the gas technology.
Structure and Bonding 01/2009; 132. DOI:10.1007/430_2008_6 · 1.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A magnesium metal–organic framework with a distorted (10, 3)-a-net topology has been synthesized under solvothermal conditions, and characterized by X-ray structure determination, thermogravimetric analysis, X-ray powder diffraction, IR, and nonlinear optical studies.
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