Molecular Conformation of Hydrogen-Bonded Ethylene Glycol in Sodalite: A 1H CRAMPS NMR, IR, and 2H NMR Study

Abstract

Analysis of the variable-temperature H-1 CRAMPS NMR, IR, and H-2 NMR spectra obtained from the ethylene glycol molecules in two sodalite materials with Si/Al ratios of infinity and ca. 5 reveals that the intermolecular hydrogen bonds between the framework oxygens and the OH groups of the guest molecule, which appear only in the isomorphously Al-substituted zeolite, are preserved even at 200 degreesC, which is higher than the crystallization temperature (175 degreesC) of the zeolite host. As a consequence, the conformations of the encapsulated ethylene glycol molecules in these two materials were found to maintain in a manner distinctly different from each other over the temperature range (25-200 degreesC) studied here.