Synthesis of Pyrrolidine Ring-Fused Fullerene Multicarboxylates by Photoreaction

Aminopolycarboxylic esters react with C60 under photolysis to produce fullerene multicarboxylates. Irradiation of tetramethyl ethylenediaminetetraacetate (EDTA) with C60 yields the EDTA-containing fullerene monoadduct C60(MeOOCCH)2NCH2CH2N(CH2COOMe)2. In addition, several other C60 monoadducts are also isolated and characterized, including compounds due to EDTA fragmentation. Similar results are observed with pentamethyldimethylenetriaminepentaacetate (DTPA). When partially methylated nitrilotriacetic acid is irradiated with C60, decarboxylation occurs and organodihydrofullerene derivatives such as C60(H)(CH2N(CH2COOMe)2) are formed. Radical mechanisms are proposed for both types of photoreactions. The fullerene derivatives are characterized by their spectroscopic data. Photoreactions of C60 with other analogous molecules also support the conclusions.