Cycloparaphenylenes (CPPs), in which benzene rings are bound to each other at their
para positions, represent the shortest sidewall segment (carbon nanoring) of single-walled carbon nanotubes (SWCNTs). Itami
et al. reported the first synthesis of
[12]cycloparaphenylene ([12]CPP), which is composed of twelve benzene rings. Moreover, by using [12]CPP as a “template” to grow a nanotube , the selective synthesis of structurally uniform SWCNTs is also expected in the future, as well as various applications such as organic electronics and host-guest chemistry.