Synthesis and Electrochemistry of Novel Dumbbell-Shaped Bis-pyrazolino[60]fullerene Derivatives Formed Using Microwave Radiation.

The design of covalently linked [60]fullerene dimers has gained increased attention, as the linked electron donors or acceptors are in close proximity to the surface of the C(60), providing a valuable approach to novel molecular electronic devices. Herein, new compounds involving C(60) dumbbells covalently connected by the π-conjugated system from azobenzene and diaryl ether linkers were synthesized following the bifunctional cycloaddition reactions to C(60) using microwave radiation. The structural identity of the fullerene dimers has been determined using spectroscopic techniques including Fourier transform infrared (FT-IR), matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF), and NMR spectroscopy, and the photophysical and the electrochemical properties for the new dumbbells have been examined using UV-vis spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and square wave voltammetry. Both new dimers show electronic interaction with the fullerene cage and higher electron affinity than the pristine C(60).