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Exohedral Functionalization and Applications of the Trimetallic Nitride Endohedral Metallofullerenes

This dissertation addresses the exohedral cage functionalization and potential applications of the Sc₃N@C₈₀ and Sc₃N@C₇₈ trimetallic nitride endohedral metallofullerenes. In addition, this dissertation discusses miscellaneous research that is relevant to the aformentioned metallofullerenes and their applications, such as the discovery of a new cage isomer <i>(D<sub>5h</sub>)</i> of Sc₃N@C₈₀, the synthesis of Lu₃N@C₈₀ as a novel X-ray contrasting agent, and the synthesis of Sc₃¹⁵N@C₈₀ with ¹⁵N₂ gas.

The first derivative of Sc₃N@C₈₀ was synthesized by functionalizing the exterior of the cage via a [4 + 2] cycloaddition reaction with a ¹³C-labeled intermediate. Addition occurred across the [5,6] ring-juncture of the cage to form a mono-adduct, which has a mirror plane of symmetry as observed from the time-averaged ¹³C NMR spectrum. The structure of the mono-adduct was confirmed by X-ray crystallography. Diethyl and dibenzyl malonate adducts of Sc₃N@C₈₀ were synthesized, in addition to a ¹⁵N-labeled terminal amine derivative. Water-soluble metallofullerenols, Sc₃N@C₈₀(OH)<sub>~10</sub>(O)<sub>~10</sub>, were synthesized from polyanionic intermediates.

The Sc₃N@C₇₈ metallofullerene was derivatized with a ¹³C-labeled reagent to afford mono-, di- and tri-adducts. A single structural isomer of the mono-adduct was found, while several isomers of the di- and tri-adducts were observed by HPLC. ¹³C and ¹H NMR data of the mono-adduct support a structure that results from addend addition to an asymmetric site on the C₇₈ carbon cage.

The HPLC isolation and characterization of Lu₃N@C₈₀ is discussed. When irradiated with X-rays, Lu₃N@C₈₀ provided a small level of contrast that can only be attributed to the large atomic number (Z) of the lutetium atoms. Mixed-metal species that contains gadolinium and lutetium or holmium and lutetium could be employed as multifunctional contrasting agents for X-ray, MRI and radiopharmaceuticals, thereby eliminating the need for three separate agents.

A new cage isomer of the Sc₃N@C₈₀ metallofullerene was synthesized and partially isolated by HPLC. This carbon cage possesses <i>D<sub>5h</sub></i> symmetry, as indicated by the time-averaged six line ¹³C NMR spectrum with a 1:2:2:1:1:1 ratio.

The internal metal-nitride cluster of Sc₃N@C₈₀ was synthesized with a ¹⁵N-label for studying the motion(s) of the cluster (within the carbon cage) at various temperatures using ¹⁵N NMR spectroscopy. / Ph. D.

Identiferoai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/29325
Date24 October 2003
CreatorsIezzi, Erick B.
ContributorsChemistry, Dorn, Harry C., Deck, Paul A., Tanko, James M., Long, Timothy E., Hanson, Brian E.
PublisherVirginia Tech
Source SetsVirginia Tech Theses and Dissertation
Detected LanguageEnglish
TypeDissertation
Formatapplication/pdf
RightsIn Copyright, http://rightsstatements.org/vocab/InC/1.0/
RelationE.B.Iezzi-PhD-dissertation.pdf

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