title: High-pressure in situ 129Xe NMR spectroscopy and computer simulations of breathing transitions in the metal-organic framework Ni2(2,6-ndc)2(dabco) (DUT-8(Ni)).
abstract: Recently, we have described the metal-organic framework Ni(2)(2,6-ndc)(2)(dabco), denoted as DUT-8(Ni) (1) (DUT = Dresden University of Technology, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane). Upon adsorption of molecules such as nitrogen and xenon, this material exhibits a pronounced gate-pressure effect which is accompanied by a large change of the specific volume. Here, we describe the use of high-pressure in situ (129)Xe NMR spectroscopy, i.e., the NMR spectroscopic measurements of xenon adsorption/desorption isotherms and isobars, to characterize this effect. It appears that the pore system of DUT-8(Ni) takes up xenon until a liquid-like state is reached. Deeper insight into the interactions between the host DUT-8(Ni) and the guest atom xenon is gained from ab initio molecular dynamics (MD) simulations. van der Waals interactions are included for the first time in these calculations on a metal-organic framework compound. MD simulations allow the identification of preferred adsorption sites for xenon as well as insight into the breathing effect at a molecular scale. Grand canonical Monte Carlo (GCMC) simulations have been performed in order to simulate adsorption isotherms. Furthermore, the favorable influence of a sample pretreatment using solvent exchange and drying with supercritical CO(2) as well as the influence of repeated pore opening/closure processes, i.e., the "aging behavior" of the compound, can be visualized by (129)Xe NMR spectroscopy.
authors.affiliation: Bioanalytische Chemie, Technische Universität Dresden, Fachrichtung Chemie und Lebensmittelchemie, 01062 Dresden, Germany.
authors.forename: Herbert C
authors.initials: HC
authors.lastname: Hoffmann
authors.forename: Bassem
authors.initials: B
authors.lastname: Assfour
authors.forename: Fanny
authors.initials: F
authors.lastname: Epperlein
authors.forename: Nicole
authors.initials: N
authors.lastname: Klein
authors.forename: Silvia
authors.initials: S
authors.lastname: Paasch
authors.forename: Irena
authors.initials: I
authors.lastname: Senkovska
authors.forename: Stefan
authors.initials: S
authors.lastname: Kaskel
authors.forename: Gotthard
authors.initials: G
authors.lastname: Seifert
authors.forename: Eike
authors.initials: E
authors.lastname: Brunner
mesh_terms: D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D014978:Xenon / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D014978:Xenon; D009532:Nickel