Comparison of Nuclear Spin Relaxation of H2O@C60 and H2@C60 and Their Nitroxide Derivatives
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- 作者：Yongjun Li ; Judy Y.-C. Chen ; Xuegong Lei ; Ronald G. Lawler ; Yasujiro Murata ; Koichi Komatsu ; Nicholas J. Turro
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2012
- 出版时间：May 3, 2012
- 年：2012
- 卷：3
- 期：9
- 页码：1165-1168
- 全文大小：236K
- 年卷期：v.3,no.9(May 3, 2012)
- ISSN：1948-7185
文摘
The successful synthesis of H2O@C60 makes possible the study of magnetic interactions of an isolated water molecule in a geometrically well-defined hydrophobic environment. Comparisons are made between the T1 values of H2O@C60 and the previously studied H2@C60 and their nitroxide derivatives. The value of T1 is approximately six times longer for H2O@C60 than for H2@C60 at room temperature, is independent of solvent viscosity or polarity, and increases monotonically with decreasing temperature, implying that T1 is dominated by the spin-rotation interaction. Paramagnetic nitroxides, either attached covalently to the C60 cage or added to the medium, produce strikingly similar T1 enhancements for H2O@C60 and H2@C60 that are consistent with through-space interaction between the internal nuclear spins and the external electron spin. This indicates that it should be possible to apply to the endo-H2O molecule the same methodologies for manipulating the ortho and para spin isomers that have proven successful for H2@C60.