A2H NMR study of molecular motions of nonadecanehyphen;d40in a urea inclusion adducta)

摘要

The3H NMR spectrum of nonadecanehyphen;d40included in a urea adduct has been recorded at several temperatures in the range 145ndash;273 K. This inclusion adduct is found to undergo a phase change in the range 160ndash;170 K. In the high temperature phase the spectra indicate that the included alkane molecules are freely rotating. The amplitude of rotation is greatly diminished in the low temperature phase; however, the spectra are not those characteristic of the2H NMR rigid limit. We also present direct evidence that the chain segments next to and including the methyl groups are undergoing motions of greater amplitude than those corresponding to free chain rotation.