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_5h)</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)_~10(O)_~10, 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_5h</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.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Chemistry

Department dc:contributor.department

Chemistry

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2003

Author dc:creator

• Iezzi, Erick B.

Chair dc:contributor.committeechair

• Dorn, Harry C.

Committee members dc:contributor.committeemember

• Deck, Paul A.
• Tanko, James M.
• Long, Timothy E.
• Hanson, Brian E.

• endohedral
• metallofullerene
• scandium nitride
• X-ray contrast
• functionalization

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-10212003-130521

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/29325