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Chloro-, aryl-, and perfluoroalkylfullerenes

Date

2009

Authors

Kuvychko, Igor V., author
Strauss, Steven H., advisor
Prieto, Amy L. (Amy Lucia), committee member
Hochheimer, Hans D., committee member
Rappé, Anthony K., 1952-, committee member
Elliott, Cecil Michael, committee member

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Abstract

The preparation, properties, stability, and handling of three classes of fullerene derivatives, chloro-, aryl-, and perfluoroalkylfullerenes, were studied in detail, in some cases for the first time. The same general methodology was used throughout this work: i) analytical methodology was developed and optimized using internal standards of known composition and purity; ii) the preparation of new compounds was studied by mapping the space of different reaction conditions using the newly developed analytical methods; iii) the efficient synthetic methods for the preparation of individual pure compounds were developed based on the mapping; iv) the pure compounds were characterized and their stability, or lack thereof, was studied. The first detailed study of fullerene chlorination led to isolation and characterization of several new chlorofullerenes: o-C60Cl2; p-C60Cl2; C60Cl4; C60Cl10; C70Cl6; and C70Cl8. It was discovered that chlorofullerenes are generally photosensitive in solution, both in the presence and absence of air and moisture. Effective methods for handling chlorofullerenes were developed (including a specialized crystallization technique). The experimental findings and theoretical calculations revealed the fundamental patterns governing multiple additions to fullerene cages. The efficient preparation of aryl- and perfluoroalkylfullerenes from chlorofullerene synthons was developed, leading to high yields of aryl- and mixed perfluoroethyl/hydrofullerenes (i.e., C60(C2F5)5H and C60(C2F5)3H). The first example of an organometallic complex of a perfluoroalkylfullerene was prepared using C60(C2F5)5H as a synthon. The direct addition of thermally-generated CF3 radicals to fullerenes was also studied. A specialized reactor was designed and built in order to validate mechanistic hypotheses. Good agreement between the experimental observations and predictions based on the hypotheses was observed. It led to the development of a new approach to efficient synthesis of C60(CF3)n with low values of n, including an unprecedented selective synthesis of C60(CF3)2 from unpurified fullerene extract.

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Department Head: Anthony K. Rappďż˝.

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