Mechanism and number of adducts of photo-addition of glycine methyl-ester to [60] fullerene

Recently, it has been shown that visible light irradiation of a mixture of C60 and glycine methyl-ester in the presence of oxygen is a direct route to sequentially synthesize higher FP poly-adducts. However, the involved mechanism and the maximum number of pyrrolidine adducts per C60 molecule remained to be ascertained. Using high resolution mass spectrometry and HPLC–MS, we show here that the most probable mechanism involves a first step of azomethine ylide (AMY) formation followed by its [2+3] cyclo-addition to C60, and that the hexakis-adduct is the highest FP poly-adduct (FPPA) obtained under these conditions. Some FPPA and AMY dimers are also identified in the final mixture.