Inserting Fullerene Dimers into Carbon Nanotubes: Pushing the Boundaries of Molecular Self‐assembly

Carbon nanotubes can encapsulate several molecular species forming one‐dimensional crystals. Using previously reported methods we produced directly‐bonded, asymmetric C60‐C70 dimers and oxygen‐bridged dimers of the type C60‐O‐C60. We present here microscopic evidence of filling single‐walled carbon nanotubes (SWNTs) with the above fullerene dimers. The most important filling constraint is found to be the nanotube size. SWNTs with diameters around 1.6 nm incorporate dimers considerably more easily than SWNTs with smaller diameters. This kind of molecular self‐assembly opens up the potential for using nanotubes and fullerenes for nanodevices.