Construction of fullerene-coated nano-structures using alkylfullerenyl cations

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1.Quantitative Determination of the Thermodynamic Stabilities of Alkylfullerenyl CationsThe thermodynamic stabilities of alkylfullerenyl cations were evaluated by the kinetic measurements for the S_N1 solvolysis of chlorides R-C_<60>-Cl and by precise determination of the equilibrium constants of the ionization of fullerenols R-C_<60>-OH. The results of these experiments demonstrated that alkylfullerenyl cations have stabilities comparable to that of the tert-butyl cation.2.Preparation of Alkylfullerenyl Cation as Long-lived Species in Solution and Its Isolation as a SaltThe isolation of C_<60> cations have been considered extremely difficult, owing to the electronegative nature of the C_<60> cage. In the present study, however, treatment of chlorides R-C_<60>-Cl with silver ion (AgSbF_6) or with a Lewis acid (SbCl_5) resulted in successful preparation of RC_<60>^+ the form of a stable solution in neutral organic solvent or in the form of a salt RC_<60>^+ SbCl_5^-. Formerly, these cations could be prepared only as solutions in strongly acidic solvents.3.Coating of Silica Surface with Fullerene Monolayer using Alkylflullerenyl CationA monolayer of fullerene could be prepared on the surface of silicon wafer, by dipping the wafer in a solution of R-C_<60>-Cl. This can be interpreted as a result of the reaction of an intermediate cation RC_<60>^+ with hydroxyl groups on the surface of the oxide layer. This observation demonstrated that the high reactivity of RC_<60>^+ would be useful for the formation of a C_<60> monolayer on solid surfaces covered with hydroxyl groups.