Bisfunctionalized fullerene derivatives

Based on the depicted equilibrium and the observed lifetime a rate constant for the forward reaction of 10 NT s" was estimated. The slow protonation rate of the one-electron reduced fullerene n-radical anions can be understood in terms of the charge delocalization and also the hybridization of the generated carbanion. Furthermore, the heterogeneous and hydrophobic environments of the host s interior can be assumed to be beneficial for the slow-down of the protonation dynamics. In homogeneous aqueous solutions the protonation rate should be faster, a hypothesis that was substantiated by recent radiolytic experiments with bisfunctionalized fullerene derivatives. The latter compounds are soluble in aqueous solutions without employing a solubiiizer (host) and give rise to protonation rate constants of 3 x 10 M s" (38). 

From the first-order rate constant versus concentration dependency a bimolecular rate constant of 2.9 x lO M s was derived for reaction 29. All bisfunctionalized fullerene derivatives investigated were successfully reduced by means of hydrated electrons ((0.75 - 3.4) x lO M s ) and (CH3)2 COH radicals ((0.9 - 2.2) x 10 IvT s ) (Table 6). These values are, however, significantly lower than those for the reduction of Ceo/surfactant (C6oC(COO )2)/surfactant and the respective y-CD encapsulated complexes. Such an effect reflects the perturbation of the fullerene tt-system caused by placing two functional negatively charged appendices onto the fullerene core. 

Table 6 Rate Constant for the Radiation-Induced Reduction of Various Bisfunctionalized Fullerene Derivatives in Homogeneous (H2O, 10 vol % 2-propanol, pH 9.7) and Heterogeneous...

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