Single and double reduction of C60 in 2:1 γ- cyclodextrin/[60]fullerene inclusion complexes by cyclodextrin radicals

Spectroscopic and chemical properties of γ-CD• radicals, resulting from the abstraction by HO• radicals of hydrogen atoms, have been investigated using pulse radiolysis. The reactions of γ-CD• radicals with C60 in 2:1 γ-CD/C60 inclusion complexes have been studied in aqueous solutions. It has been demonstrated that the γ-CD_ radicals are reducing species producing C60 monoanion radicals, as well as doubly reduced C60 , well characterized by their absorption spectra in the near IR. The oxidation potential of γ-CD• radical is estimated to be more negative than –390 mV vs. NHE. The kinetics of the C60 reduction by γ-CD• radicals have been determined and compared with kinetics by other reducing species including the solvated electron (eaq) and CO2 radicals. It was observed that the method of preparation of the 2:1 γ-CD/C60 inclusion complexes modifies the C60 reduction mechanism.