FULLERENES AND COUNTERCURRENT CHROMATOGRAPHY

Fullerenes are a new allotropic form of carbon. These all-carbon molecules have a tridimensional structure looking like spheres. All the carbon atoms are sp(2)-hybridized. The fullerenes are formed in the soot obtained when an electric arc is formed between two pure graphite electrodes under reduced helium pressure. C-60 is predominantly obtained (approximate to 80%) then C-70 (approximate to 10%) and higher fullerenes. They are very difficult to separate by classical liquid chromatography (LC) due to their poor solubility in common LC solvents. Countercurrent chromatography (CCC) uses biphasic liquid systems. One liquid phase is the stationary phase, the other is the mobile phase. Its capability in fullerene separation was evaluated. Two liquid systems were studied. One is heptane-DMSO-dichlorobenzene (DCB), the second one is isooctane-DMF-DCB. Their mass phase diagrams are given at 20 degrees C and 0 degrees C. The C-60 partiton coefficient was measured in several compositions of these systems. The fullerene separation capability of CCC is demonstrated by several chromatograms.