Efficient microwave-assisted synthesis of PCBM methanofullerenes (C60 and C70)

PCBM is a fullerene derivative (phenyl-C61-butyric acid methyl ester) considered to be one of the best n-type organic semiconductors and plays a relevant role in organic photovoltaic solar cells. Much effort has been devoted to the optimization of the synthesis of PCBM derivatives. In this paper, PC61BM and PC71BM fullerene mono-adducts but also PCBM-like derivatives are successfully prepared by a one-step cyclopropanation reaction under microwave irradiation. The products are collected in good yields in short time, during which isomerization of the open [5,6] to the closed [6,6] form takes place in situ. In addition, with the use of two cycles of irradiation, a series of mixtures of bis-adduct PCBM-like derivatives were also obtained in good yields.