Thierry Loiseau1, Christian Serre1, Clarisse Huguenard2, Gerhard Fink2, Muriel Sebban2, Marc Henry2, Thierry Bataille3
1Institut Lavoisier, UMR CNRS 8637, Université de Versailles St-Quentin en Yvelines, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France; Fax(33)1 39 25 43 58
2Tectonique Moléculaire du Solide, UMR CNRS 7140, Université Louis Pasteur, Institut Le Bel, 4 Rue Blaise Pascal, 67070 Strasbourg Cedex, France
3LCSIM UMR CNRS 6511, Cristallographie des Poudres et Réactivité des Solides, Université de Rennes I, Avenue du Général Leclerc, 35042 Rennes Cedex, France
Tóm tắt
AbstractAluminum 1,4‐benzenedicarboxylate Al(OH)[O2CC6H4CO2]⋅ [HO2CC6H4CO2H]0.70 or MIL‐53 as (Al) has been hydrothermally synthesized by heating a mixture of aluminum nitrate, 1,4‐benzenedicarboxylic acid, and water, for three days at 220 °C. Its 3 D framework is built up of infinite trans chains of corner‐sharing AlO4(OH)2 octahedra. The chains are interconnected by the 1,4‐benzenedicarboxylate groups, creating 1 D rhombic‐shaped tunnels. Disordered 1,4‐benzenedicarboxylic acid molecules are trapped inside these tunnels. Their evacuation upon heating, between 275 and 420 °C, leads to a nanoporous open‐framework (MIL‐53 ht (Al) or Al(OH)[O2CC6H4CO2]) with empty pores of diameter 8.5 Å. This solid exhibits a Langmuir surface area of 1590(1) m2 g−1 together with a remarkable thermal stability, since it starts to decompose only at 500 °C. At room temperature, the solid reversibly absorbs water in its tunnels, causing a very large breathing effect and shrinkage of the pores. Analysis of the hydration process by solid‐state NMR (1H, 13C, 27Al) has clearly indicated that the trapped water molecules interact with the carboxylate groups through hydrogen bonds, but do not affect the hydroxyl species bridging the aluminum atoms. The hydrogen bonds between water and the oxygen atoms of the framework are responsible for the contraction of the rhombic channels. The structures of the three forms have been determined by means of powder X‐ray diffraction analysis. Crystal data for MIL‐53 as (Al) are as follows: orthorhombic system, Pnma (no. 62), a = 17.129(2), b = 6.628(1), c = 12.182(1) Å; for MIL‐53 ht (Al), orthorhombic system, Imma (no. 74), a = 6.608(1), b = 16.675(3), c = 12.813(2) Å; for MIL‐53 lt (Al), monoclinic system, Cc (no. 9), a = 19.513(2), b = 7.612(1), c = 6.576(1) Å, β = 104.24(1)°.
