Fullerene Formation and Annealing

摘要

Why does the highly symmetric carbon cluster C_(60) form in such profusion under the right conditions? This question was first asked in 1985, when Kroto et al. (I) suggested that the predominance of the C_(60) carbon clusters observed in the molecularbeam experiments could be explained by the truncated icosahedral (or soccer ball) form (see figure). The name given to this cluster, buckminsterfullerene, led to the use of the term fullerenes for the family of hollow-cage carbon clusters made up of even numbers of triply coordinated carbons arranged with 12 pentagonal rings and an almost arbitrary number of hexagonal rings. More than a decade later, we still lack a completely satisfying understanding of the fundamental chemistry that takes place during fullerene formation. Most current models for fullerene formation require a facile mechanism for ring rearrangement in the fullerene structure, but the simplest proposed mechanisms are believed to have unrealistically high activation barriers. In this issue, Eggen et al. (2) report calculations suggesting that atomic carbon in the reaction mixture could act as a catalyst and allow substantially lower activation barriers for fullerene annealing.