Fullerenes and fullerene adducts: I. Oxidation by charcoal. II. Singlet oxygen involvement in the reaction with amines. III. Photophysics of a series of adducts. IV. Electron transfer from guanosine and 8-oxo-guanosine

Chapter 1. General introduction to fullerenes.; Chapter 2. Reaction of C60 with 1-diethylamino-1-propyne (DAP) leads to cyclobutene adduct 1, which upon acid hydrolysis provides a facile synthetic route to fullerene adduct 3. Subsequent oxidative cyclization involving activated carbon (activated carbon) yields the novel fullerene lactone 4.; Chapter 3. Photochemical addition of 3-diethylamino-1-propyne (DEAP) to C60 leads to a novel fullerene adduct (1). The addition of DEAP to C60 did not occur in the expected [2+2] fashion. Instead addition took place at the methylene carbons alpha to the nitrogen, resulting in the replacement of two C-H bonds with C60-C bonds. This reaction provides a facile route to a fullerene adduct containing an alkyne moiety. Study of the mechanism of addition disclosed the unexpected involvement of singlet oxygen. Other previously-reported additions of amines to fullerenes also appear to involve singlet oxygen.; Chapter 4. The main properties of the triplet states and the yields of singlet oxygen generation for a series of methano[60]fullerene adducts with increasing numbers of substituents were determined. The triplet properties investigated are energies, triplet-triplet absorption spectra, extinction coefficients and quantum yields as well as singlet oxygen quantum yields.; Chapter 5. Irradiation of a dihydrofullerene linked to a deoxynucleotide causes base-labile sites in guanosine residues on a complementary oligonucleotide strand. The mechanism appears to be electron transfer, inefficient electron transfer from guanosine to 3C60, and more efficient transfer from (the more easily oxidized) 8-oxoguanosine, the primary oxidation product of guanosine. Transfer from G-G diads should also be more efficient than from guanosine. It is probable that singlet oxygen or one-electron oxidation of guanosines forms the easily-oxidized 8-oxo compound, which is rapidly oxidized further to give base-labile sites that can cause DNA cutting.