Small Caged Molecules inhibiting

Davidson (1971) determined that the most important rotation inhibition interactions between guest molecules (in adjacent cages) were the dipole-dipole interactions, but even they were of minor importance. Within a single cage, both nonpolar and polar guest molecules such as EO, THF, and acetone have only small barriers to rotational freedom, which approximates that in the vapor phase. The rotational freedom is probably due to the fact that the sum of the cage water dipoles effectively cancel near the center of each cage, and even the quadrupolar fields are relatively small. 

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