MIL-96, a Porous Aluminum Trimesate 3D Structure Constructed from a Hexagonal Network of 18-Membered Rings and μ 3 -Oxo-Centered Trinuclear Units
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. Journal of the American Chemical Society
(Impact Factor: 12.11).
09/2006; 128(31):10223-30. DOI: 10.1021/ja0621086
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).
Available from: Laith Hussein
- "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. "
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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.
Available from: Renju Zacharia
- "Topologically, all the MOFs consist of metal centers, more precisely known as secondary building units (SBUs) connected with each other by the organic molecules, commonly known as organic linkers . Different types of metals have been employed and examined for the structure forming capacity of MOFs; typical examples are zinc [9–15,28], copper  , chromium   , aluminum  , iron  , scandium , manganese , zirconium , vanadium  or cadmium . Organic linker is probably the far most important part in tailoring the architecture of metal-organic frameworks. "
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ABSTRACT: Benzenetribenzoate (BTB) ligand is combined with four trivalent metals, Al, Cr, Fe and Ga by solvothermal synthesis to form four different metal-organic frameworks (MOFs), abbreviated as M-BTB, where M stands for the metal. Each of the MOFs is characterized with pore texture, scanning electron microscopic images (SEM), X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR) and thermogravimetric analysis (TGA). Pore texture reveals the highest BET surface area belongs to Al-BTB (1045 m2/g) and decreases in the order of Cr > Fe > Ga. Hydrogen adsorption at 77 K and up to ambient pressure indicates that Al-BTB adsorbs highest amount of H2 (0.98 wt.%) and decreases in the same order as the specific surface areas. High pressure H2 adsorption at room temperature (298 K) and pressure up to 80 bar reveals that Fe-BTB adsorbs highest amount of hydrogen (0.51 wt.% or 2.75 g L−1, absolute) and the adsorption amount decreases in the order of Cr > Al > Ga.
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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.
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