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Chromatography and purification of endohedral metallofullerenes

At the conception of this research, a separation methodology for obtaining purified mctallofullerene [A<sub>m</sub>@C<sub>2n</sub>, m = # of metal atoms, A, and C<sub>2n</sub> = # of carbons in the surrounding cage] samples was not yet developed. Isolation of these metal-encapsulated fullerenes was strongly desired for characterization of their physical and chemical properties. Predicted applications for these novel species include their use as possible superconductors, catalysts, and non-linear optical devices. However, initial purification efforts have been hindered by several difficulties. These factors include a low abundance (< 1%) in the raw extract, uncertain stability in aerobic environments, co-elution of A<sub>m</sub>@C<sub>2n</sub> with empty-cage fullerenes, and the need for selective chromatographic detection.

In this research, these difficulties have been overcome with the development of a continuous-flow, on-line HPLC-EPR apparatus. Advantages include a selective, non-invasive detector with chromatographic separations being performed in a controlled anaerobic environment. This on-line approach permits the selective detection of only those metallofullerenes with an odd-number of encapsulated atoms. The ability to continually monitor separations of these paramagnetic species ultimately permits the optimization of chromatographic parameters. The methodology developed from this on-line HPLC-EPR approach has ultimately resulted in purified empty-cage (C₆₀, C₇₀...C₉₆) and metallofullerene samples (Sc₂@C₇₄, Sc₂@C₇₆, Sc₂@C₇₈, Sc₂@C₈₀, Sc₂@C₈₂, Sc₂@C₈₄ - two isomers, Sc₂@C₈₆, Sc₂@C₈₈, Sc₂@C₉₀, Sc₃@C₈₂, Sc₄@C₈₂, La₂@C₇₂, Er@C₈₂, Er₂@C₈₂ - two isomers, and Er₂@C₉₂). / Ph. D.

Identiferoai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/29176
Date03 October 2005
CreatorsStevenson, Steven A.
ContributorsChemistry, Dorn, Harry C., Anderson, Mark R., Brewer, Karen J., Taylor, Larry T., Bell, Harold M.
PublisherVirginia Tech
Source SetsVirginia Tech Theses and Dissertation
LanguageEnglish
Detected LanguageEnglish
TypeDissertation, Text
Formatxx, 171 leaves, BTD, application/pdf, application/pdf
RightsIn Copyright, http://rightsstatements.org/vocab/InC/1.0/
RelationOCLC# 34648512, LD5655.V856_1995.S748.pdf

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