Fullerenes comprise an infinite class of pure carbon cages.
The variety of fullerene structures, their strength and stability, and their ability to undergo chemical derivatization make them ideal building blocks for a nanoscale architecture. Formation of single-walled carbon nanotubes, which are likely to be the ultimate nanoscale building beams, are discussed in detail. Fullerene Zoology and Synthesis Carbon is unique in the periodic table in its ability to form pure covalently bonded extended structures of great strength. Metals also form pure crystals, but the extreme delocalization of their valence electrons favors weak, less directional bonding with many neighbors. The variety of pure carbon structures would be limited to diamond, graphite, and exotic and highly reactive sp-hybridized molecules if appeal could be made only to the various ways carbon atoms can hybridize.