Benzene-d6 and toluene-d8 as guest molecules in micropores of a layered zirconium phosphonate: 2 H, 13 C{1 H}, and 31 P{1 H} solid-state NMR, deuterium NMR relaxation, and molecular motions. Academic Article uri icon

abstract

  • For the first time, pore spaces in the Zr (IV) phosphonate (1) as a representative of layered metal (IV) phosphonate materials have been investigated by studying mobility of guest molecules, benzene-d6 , and toluene-d8 . Guest molecules located in micropores of 1 have been characterized by solid-state 13 C{1 H} and 2 H NMR spectra in static samples with varying temperatures. At moderately low temperatures, the benzene and toluene molecules experience fast isotropic reorientations and show the motionally averaged liquid-like carbon and deuterium line shapes in the NMR spectra. At lower temperatures, two anisotropic motional modes have been found for benzene molecules by analyzing the 2 H NMR line shapes: the well-known in-plane C6 rotation and composite motions. Interpretation of the variable-temperature 2 H T1 relaxation times identifies the composite motions as 120 flips around the C6 axis perpendicular to the molecular plane and the rotations around the molecular para-C-C axis. The data obtained resulted in the idealized (cylinder-shaped) model of micropores in compound 1 with the diameter of 20-30. Furthermore, the activation energy of 20.1kJ/mol determined for the benzene motions classifies the molecule-surface interactions as weak but enough for absorption.

published proceedings

  • Magn Reson Chem

author list (cited authors)

  • Contreras, A. R., Bakhmutov, V. I., Elliott, D. W., & Clearfield, A.

complete list of authors

  • Contreras, Aida R||Bakhmutov, Vladimir I||Elliott, Douglas W||Clearfield, Abraham

publication date

  • January 1, 2018 11:11 AM

publisher