Fullerenes: Identification of Isomers Based on Nuclear Magnetic Resonance Spectra
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Buckminsterfullerene C60 was first detected in the time-of-flight mass spectrometer from the product of laser vaporization of graphite and later obtained in large quantity from electric arc resistive heating of graphite rods. The four characteristic peaks in the infrared (IR) spectrum of C60 revealed its truncated icosahedron structure, which was further confirmed by nuclear magnetic resonance (NMR) spectroscopy. Separation and characterization of fullerenes C70, C76, C78, C82, and those with even higher carbon atom counts followed. High-performance liquid chromatography (HPLC) has proved to be a powerful technique to separate fullerene isomers, while 13C NMR is the method of choice to characterize them.