Benzene‐d6 and toluene‐d8 as guest molecules in micropores of a layered zirconium phosphonate: 2H, 13C{1H}, and 31P{1H} 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 Å. Furthermore, the activation energy of 20.1 kJ/mol determined for the benzene motions classifies the molecule-surface interactions as weak but enough for absorption.

author list (cited authors)

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

citation count

  • 1

publication date

  • December 2018

publisher