129Xe NMR study of the framework flexibility of the porous hybrid MIL-53(Al).
The metal-organic framework MIL-53 exhibits a structural transition between two possible porous structures, so-called large-pore (lp) and narrow-pore (np) forms, depending on the temperature or when guest molecules are adsorbed. (129)Xe NMR has been used to study the lp --> np transition induced by the adsorption of xenon as revealed by the adsorption isotherms. The NMR spectra show that the two structures, characterized by two distinct lines, coexist for xenon pressures above 5 x 10(4) Pa at room temperature, but a complete transformation is achieved when the temperature is decreased. An original interpretation of the NMR results allowed us to quantify the rate of the structural transformation. In particular, at room temperature, we have shown that 28% of the channels remain open. Two possible interpretations of the hysteresis observed in the chemical shift variation versus xenon pressure are proposed.
Springuel-Huet
Marie-Anne
MA
Laboratoire de Chimie de la Matière Condensée, UMR CNRS 7574, Université Pierre et Marie Curie, Univ. Paris 06, F 75252 Paris Cedex 05, France. marie-anne.springuel-huet@upmc.fr
Nossov
Andrei
A
Adem
Ziad
Z
Guenneau
Flavien
F
Volkringer
Christophe
C
Loiseau
Thierry
T
Férey
Gérard
G
Gédéon
Antoine
A
D000535:Aluminum / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009942:Organometallic Compounds / Q000737:chemistry*; D016062:Porosity; D014979:Xenon Isotopes / Q000737:chemistry
D009942:Organometallic Compounds; D014979:Xenon Isotopes; D000535:Aluminum