title: The origin of the measured chemical shift of129Xe in UiO-66 and UiO-67 revealed by DFT investigations.
abstract: The NMR chemical shift of the xenon isotope129Xe inside the metal-organic frameworks (MOFs) UiO-66 and UiO-67 (UiO - University of Oslo) has been investigated both with density functional theory (DFT) and in situ high-pressure129Xe NMR measurements. The experiments reveal a decrease of the total chemical shift comparing the larger isoreticular MOF (UiO-67) with the smaller one (UiO-66), even though one may expect an increase due to the higher amount of adsorbed Xe atoms. We are able to calculate contributions to the chemical shift individually. This allows us to evaluate the shift inside the different pores independently. To compare the theoretical results with the experimental ones, we performed molecular dynamics simulations of Xe in the MOFs. For this purpose, the pores were completely filled with Xe to gain insight into the distribution of Xe at high pressures. The resulting trend of the total shift agrees well between the theoretical predictions and the experiments. Moreover, we are able to describe specific contributions to the total shift per pore, explaining the experimental behavior at an atomistic level.
authors.affiliation: Technische Universität Dresden, Theoretical Chemistry, Germany. kai.trepte@chemie.tu-dresden.de.
authors.forename: Kai
authors.initials: K
authors.lastname: Trepte
authors.forename: Jana
authors.initials: J
authors.lastname: Schaber
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schwalbe
authors.forename: Franziska
authors.initials: F
authors.lastname: Drache
authors.forename: Irena
authors.initials: I
authors.lastname: Senkovska
authors.forename: Stefan
authors.initials: S
authors.lastname: Kaskel
authors.forename: Jens
authors.initials: J
authors.lastname: Kortus
authors.forename: Eike
authors.initials: E
authors.lastname: Brunner
authors.forename: Gotthard
authors.initials: G
authors.lastname: Seifert