Nanofibers of fullerene C₆₀ through interplay of ball-and-socket supermolecules

Mixing solutions of p-tBucalix[5]arene and C₆₀ in toluene results in a 1:1 complex (C₆₀)∩(p-tBu-calix[5]-arene), which precipitates as nanofibers. The principle structural unit is based on a host-guest ball-and-socket nanostructure of the two components, with an extended structure comprising zigzag/helical arrays of fullerenes (powder X-ray diffraction data coupled with molecular modeling). Under argon at temperatures above 309°C, the fibers undergo selective volatilization of the calixarenes to afford C₆₀-core nanostructures encapsulated in a graphitic material sheath, which exhibits a dramatic increase in surface area. Above 650°C the material exhibits an ohmic conductance response, due to the encapsulation process.