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Allison Koopman

Allison Koopman lab photo


University of California, Santa Barbara


CCS Chemistry


Wenting Cai

Faculty Sponsor(s): 

Luis Echegoyan

Faculty Sponsor's Department(s): 

Chemistry and Biochemistry

Project Title: 

Addition of Nitrogen During Arcing and its Effect on the Production of Uranium Metallofullerenes

Project Description: 

Actinide Endohedral Metallofullerenes (EMFs) represent an intriguing and unexplored area of chemistry. Recently there have been successes in producing the mono-uranium EMF species U@C74, U@C82, and U@C86 when using arc reactor gasses O2, SO2, and CO2. However, fullerene species were missing between U@C74 and U@C82, as well as U@C84. Surprisingly, when a little N2 was added to the reactor, new species were observed for the first time. Soot containing uranium EMFs was obtained from graphite rods filled with uranium oxide and graphite powder (weight ratio of U/C = 4:1) under an atmosphere of 200 torr He, 20 torr O2, and 10 torr N2 in a conventional Kratschmer-Huffman arc-discharge reaction. The soot was then Soxhlet-extracted for three and a half hours using CS2. Besides the U@C74, U@C82, and U@C86, the most abundant species produced was U@C80, followed by U@C76 and U@C84. Multistage HPLC separation yielded pure isomers of U@C80 in a relatively large quantity. In addition, after further separations, other uranium metallofullerenes such as U2C80 and U2OC78 were obtained. (see Figure 1) From these successes, it can be concluded that N2 plays an important mechanistic role to produce these species. In this case, it helps to generate the various species of uranium EMFs in relative abundance.