Manipulation of the Interior and Exterior of Endohedral Fullerenes

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This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports Professor Alan L. Balch at the University of California at Davis to investigate the interplay between the outer surfaces of endohedral fullerenes and the metal ions contained inside. X-ray structure determinations will be performed on larger endohedrals such as M3N@C82 and M3N@C84 where theory predicts that structures violating the isolated pentagon rule (IPR) should be favored. Cocrystallization techniques that overcome many of the disorder problems that plague fullerene crystallography will be used. The external environment about the endohedral can affect the location and characteristics of the metal ions on the inside with regard to orientation and chemical interaction with the cage carbon atoms. These interactions will be systematically investigated by examining the effects of reduction on the structure of the M3N@C80 endohedrals in order to define the changes and uncover whether they are persistent. The effects of external functionalization on the structure and chemical behavior of various endohedrals will be studied; in particular, the effects of oxidants on endohedrals will be examined, since the oxidative stability of endohedrals is important to their eventual utility, reactions with organometallic reagents will be used to probe the reactive sites in endohedral fullerenes and explore differences in chemical behavior between the endohedral fullerenes and empty cage fullerenes. The factors influencing the orientation of the metal ions inside endohedral fullerenes in the crystalline state will be examined in cocrystallization studies where the nature of the non-endohedral and the cocrystallization will be varied. The synthesis and structures of hetero-endohedrals, endohedrals with azafullerene cages with metal ions inside will be examined. The magnetic properties of endohedral fullerenes with paramagnetic lanthanide ions in well-defined crystalline environments will be measured. The electrochemical preparation of redox-active films made by electrochemical deposition of endohedrals (particularly those with paramagnetic lanthanide ions inside) and transition metal complexes will be examined in electrochemical studies. Endohedral fullerenes are under active investigation for biomedical applications including use as MRI agents and as carriers of radiopharmaceuticals. This work will contribute the education of a new generation of undergraduate, graduate, and postgraduate students in synthetic and structural chemistry, with a focus on endohedral fullerenes but ultimately encompassing a range of organic and inorganic compounds.