Stabilities and reactivities of buckminsterfullerene radicals, (ButO)nC60˙, towards dioxygen, nitric oxide and spin trapping agents
Abstract
(ButO)nC60˙ radicals have been conveniently produced by addition of photochemically generated ButO' radicals to buckminsterfullerene (C60). Radical adducts (where n > 2) are very persistent under N2 at room temperature and can be observed for as long as nine days. Reactions between the radical adducts and dioxygen (O2) are slow and reactivities vary among (ButO)nC60˙ radicals. However, nitric oxide (˙NO) reacts more rapidly with (ButO)nC60˙ radicals. Among the product components are stable dibuckminsterfullerene aminoxyl (nitroxide) radicals, [(ButO)nC60]2N–O˙, which have been observed by EPR spectroscopy at concentrations of ca. 10–7 M for the first time. Surprisingly, (ButO)nC6O˙ radicals are riot reactive towards several typical radical-trapping agents (spin traps), e.g. DMPO (5,5-dimethyl-1-pyrroline N-oxide), PBN (C-phenyl N-tert-butylnitrone), NB (nitrosobenzene) and MNP (2-methyl-2-nitrosopropane), when used at typical concentrations (10–100 mM) at room temperature.