Type of Document Dissertation Author Iezzi, Erick Barton URN etd-10212003-130521 Title Exohedral Functionalization and Applications of the Trimetallic Nitride Endohedral Metallofullerenes Degree PhD Department Chemistry Advisory Committee
Advisor Name Title Dorn, Harry C. Committee Chair Deck, Paul A. Committee Member Hanson, Brian E. Committee Member Long, Timothy E. Committee Member Tanko, James M. Committee Member Keywords
- scandium nitride
- X-ray contrast
Date of Defense 2003-10-14 Availability unrestricted Abstract
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 (D5h) 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@C80metallofullerene was synthesized and partially isolated by HPLC. This carbon cage possesses D5h 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.
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