Self-Assembled Carcerand-like Cage with a Thermoregulated Selective Binding Preference for Purification of High-Purity C60 and C70

Fullerene molecules have attracted considerable interest because of the unique curved aromatic π-conjugated systems. However, the complicated and costly technologies for purification of highly pure fullerenes hamper easy access to these attractive molecules and consequently limit most of the fullerene applications. Here, we report the discovery of a carcerand-like cage acting as a stand-alone host for efficient separation and purification of C60 and C70 from fullerene soot. The cage, built through the self-assembly of metal coordination, is capable of quantitatively encapsulating fullerenes C60 and C70. The fullerene complexes are highly stable at high temperatures because of the small crevices with precisely defined sizes, multiple favorable CH-π interactions, and concave-convex aromatic interaction between fullerenes and corannulenes. Importantly, the carcerand-like cage shows a temperature-dependent selective binding preference for C60 over C70, which allows us to develop an efficient and green procedure for isolating C60 and C70 with high purity and low mass loss from fullerene soot without the help of recrystallization or high-performance liquid chromatography.