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dc.contributor.advisor Wilson, Lon J.
dc.creatorHusebo, Lars Olav
dc.date.accessioned 2009-06-04T06:49:44Z
dc.date.available 2009-06-04T06:49:44Z
dc.date.issued 2004
dc.identifier.urihttps://hdl.handle.net/1911/18646
dc.description.abstract The first exhaustive purification and characterization of fullerenol samples, prepared by reaction of C60 in toluene with NaOH solution using tetrabutylammonium hydroxide as a phase transfer catalyst, have been performed. The resulting fullerenol was determined to have a molecular formula of Na+n[C60Ox(OH) y]n- (where n = 2--3, x = 7--9, and y = 12--15 for three different, but identical, preparations). The Na +-fullerenol was found to contain both hemiketal moieties (6--8 per fullerenol) and a carbonyl moiety (1 per fullerenol) by an X-ray photoelectron spectroscopy study. In addition, Na+-fullerenol was found to be anionic with an average negative charge of 2--3 and a molar conductance in water in the range of 174--297 cm-1mol -1O-1 at 25°C. Surprisingly, the Na+-fullerenol is also paramagnetic exhibiting mueffective values in aqueous solution of 1.9--2.1 B.M. at 0.5 T and 300 K and R1 proton relaxivities of 0.55--0.77 mM-1s-1 at 20 MHz and 40°C, values both slightly higher than those expected for a pure S = ½ spin system. In solid state SQUID measurements, the Na+-fullerenols had mueffective values of ca. 1.3 B.M. (300K). ESR studies of frozen aqueous solutions at 1.5 and 5.0 K established that Na+-fullerenol is mainly S = ½ with a minor, but significant, concentration of S = 1. Thus, this is the first report to characterize the widely-studied, water-soluble fullerenols as radical anion species. The Na+-fullerenol paramagnetism was partially quenched by the addition of acid, but was reversed upon addition of base. This acid/base chemistry can be used to partition a Na+-fullerenol sample into less paramagnetic and more paramagnetic fullerenol species, with the more paramagnetic species having more S = 1 character. It is hypothesized that the paramagnetic character of Na+-fullerenol results from the formation of cyclopentadienyl radical centers on the fullerene cage, formed by an oxidation reaction with atmospheric oxygen. Sodium ions in Na+-fullerenol can be ion exchanged for other cations (e.g. Ba2+, H+, tetrabutylammonium cation, and protonated meglumine) producing fullerenols with varying magnetic and spectroscopic properties. Finally, paramagnetic Na+-fullerenol (110 mg/kg) has been shown to serve in vivo as a magnetic resonance imaging (MRI) contrast agent in a rat model, although, the rat did not survive the experiment.
dc.format.extent 106 p.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subjectInorganic chemistry
dc.title Fullerenol radical anions
dc.type.genre Thesis
dc.type.material Text
thesis.degree.department Chemistry
thesis.degree.discipline Natural Sciences
thesis.degree.grantor Rice University
thesis.degree.level Doctoral
thesis.degree.name Doctor of Philosophy
dc.identifier.citation Husebo, Lars Olav. "Fullerenol radical anions." (2004) Diss., Rice University. https://hdl.handle.net/1911/18646.


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