1. Helical microtubules of graphitic carbon
2. Carbon Nanotubes and Related Structures
3. Adapted from polyacenes cyclacenes was used to name cyclic linear polyacene compounds. Collar[n]arenes belt[n]enes and belt[n]anes were also coined to name partially and fully saturated cyclacenes in literature. To unify the nomenclatures and also to follow the tradition in naming macrocyclic compounds in supramolecular chemistry we recommend to use belt[n]arenes to name a class of belt (double-stranded) molecules in which aromatic rings are linearly fused. Collar[n]arenes belt[n]enes and belt[n]anes can be named therefore as partially or fully reduced or saturated belt[n]arene derivatives. Moreover this naming system can be easily extended to heteroaromatic ring-containing belt[n]arene analogs. For example belt[4]arene[4]pyridine or tetraza-embedded belt[8]arene is a molecular belt that contains four benzene units and four pyridine units.
4. Initiation of carbon nanotube growth by well-defined carbon nanorings