Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance.
The water-endofullerene H2O@C60 provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H2O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H2O molecules is catalysed by (13)C nuclei present in the cages.
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Salvatore
S
Mamone
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Maria
M
Concistrè
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Elisa
E
Carignani
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Benno
B
Meier
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Andrea
A
Krachmalnicoff
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Ole G
OG
Johannessen
Department of Chemistry, Columbia University, New York, New York 10027, USA.
Xuegong
X
Lei
Department of Chemistry, Columbia University, New York, New York 10027, USA.
Yongjun
Y
Li
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Mark
M
Denning
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Marina
M
Carravetta
School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
Kelvin
K
Goh
School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
Anthony J
AJ
Horsewill
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Richard J
RJ
Whitby
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Malcolm H
MH
Levitt