Synthesis and properties of pyrazolino[60]fullerene-donor systems

A series of pyrazolino[60]fullerenes has been prepared in one pot by 1,3-dipolar cycloaddition to C60 of the corresponding nitrile imine, which was generated in situ from the corresponding hydrazone. A range of donors and acceptors were introduced as substituents. Electrochemical and photophysical studies have revealed weak ground-state interactions between the organic addends and the fullerene sphere. Steady-state fluorescence has shown that, in both toluene and benzonitrile solutions, an efficient electron transfer process takes place when a strong donor is attached to the pyrazolino[60]fullerene system.