Characterization and Structures of Dimeric C70 Oxides, C140O, Synthesized with Hydrothermal Treatment

The dimeric C 70 oxides were synthesized from C 70 /C 70 O mixed powder by hydrothermal treatment at 373 K for 12 h in aqueous NaOH solution. In this treatment, nucleophilic OH - ions are abundant and nucleophilic addition reactions were considered to synthesize dimeric fullerene oxides. The yield was estimated as ca. 2−3% summing up each isomer and also produced polyoxides, it is lower than that of C 120 O. Three isomers of C 140 O were isolated using High Performance Liquid Chromatography (HPLC) and characterized with UV−vis, FT-IR, and 13 C NMR and other methods. The results of these methods show a close similarity between C 140 O and C 120 O and support that our C 140 O samples exhibit the structure of conventional furan-bridged dimers. On the basis of the results of 13 C NMR and PM3 calculations, structure assignments for each sample were attempted.