Nuclear fullerene spectra

Fig. 3.28. The electron impact mass spectrum of [60]fullerene. The insets show the expanded signals of M, and ions. The signals of the patterns are at 1, 0.5 and 0.33 u distance, respectively. The intensity scale has been normalized in the insets to allow for easier comparison of the isotopic patterns. By courtesy of W. Kratschmer, Max Planck Institute for Nuclear Physics, Heidelberg.

Fullerenes can be derivatized by various means. For example, reaction with fluorine gas proceeds stepwise to the formation of colorless CeoFeo, which, according to the 19F nuclear magnetic resonance (NMR) spectrum, contains just one type of F site and so evidently retains a high degree of symmetry.9 In view of the low adhesion typical of fluorocarbons, this spherical molecule is expected to have extraordinary lubricant properties. Curiously, bromination of Ceo is reversible on heating otherwise, the reactions of fullerenes resemble those of alkenes or arenes (aromatic hydrocarbons). 

Brunner, Pines and coworkers reported on the enhancement of NMR signals in solid Cgo and C70 using a laser-polarized xenon. NMR signals emanating from surface nuclei of solids may be enhanced by the transfer of spin polarization from laser-polarized noble gases via SPINOE (spin polarization induced nuclear Overhauser effect). The paper describes experiments in which the spin polarization is transferred under MAS from laser-polarized - Xe to a nuclear spin with a low gyromagnetic ratio in the fullerenes Ceo and C70, which are polycrystalline materials with a low surface area. In C70, a different degree of enhancement of the NMR spectrum is observed for the different atomic sites in the molecule. 

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