화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.109, No.20, 4442-4451, 2005
Dynamics of chloromethanes in cryptophane-E inclusion complexes: A H-2 solid-state NMR and X-ray diffraction study
In this paper, we present a variable temperature H-2 solid-state NMR investigation of cryptophane-E:chloroform and cryptophane-E:dichloromethane inclusion complexes. The H-2 line shapes and nuclear spin relaxation rates were analyzed in terms of the distribution of C-D bond orientations and the time scale of the guest dynamics. It was found that encaged chloroform produces broad H-2 spectra, and that its reorientation is relatively slow with a correlation time of similar to 0.17 mu s at 292 K. In contrast, the 2 H line shapes of encaged dichloromethane are narrow and the motion of this guest molecule is fast with a correlation time of similar to 1.4 ps at 283 K. The H-2 NMR data were complemented by an X-ray diffraction study of the cryptophane-E:dichloromethane structure, which was utilized in the analysis of the NMR parameters.