Electron-acceptor-induced isomerization of aryl [6,5] open fulleroids to [6,6] closed methanofullerenes and the electrochemical evaluation of their free energy difference

The thermal and photochemical rearrangements of a series of aryl substituted 6,5] open fulleroids to 6,6] closed methanofullerenes are accelerated in the presence in of electron acceptors. These 6,5] open fulleroids, facilitated by electron acceptors, rearrange thermally by a zwitteronic-type intermediate, while the photochemical reactions proceed via an excited-state electron-transfer process. The oxidation potentials of these 6,5] open fulleroids and their corresponding 6,6] closed methanofullerenes isomers have been evaluated. The free energy difference between the 6,5] open fulleroids and their corresponding 6,6] closed isomers have been estimated from the difference in their oxidation potentials.