Paramagnet enhanced nuclear spin relaxation in H2O@Open-C60 and H2@Open-C60.

Relaxation rates of endo-H2O in H2O@Open-C-60 in the presence of a nitroxide radical and of their nitroxide derivatives have been measured and are compared with effects for endo-H-2 in similar cages. T-1 relaxation enhancement of the endo-H2O and H-2 induced by either intra- or intermolecular interaction is relatively insensitive to the presence of a cage opening. Enhancement of intermolecular relaxation is observed, however, when the cage opening has an OH group.