Carbon nanohoop

Carbon nanohoops are a class of molecules consisting of aromatic sections curved out of planarity by the inherent cyclic geometry of the molecule. This class of molecules came into existence with the synthesis of cycloparaphenylenes^[1] by Ramesh Jasti in the lab of Carolyn Bertozzi and since then has been expanded into cyclonaphthylenes,^[2] cyclochrysenylenes,^[3] and even cyclohexabenzocoronenylenes.^[4] Moreover, several nanohoops containing such antiaromatic units as dibenzo[a,e]pentalene^[5] and pyrrolo[3,2-b]pyrrole are reported.^[6] Carbon nanohoops often map on to a certain chirality of carbon nanotube.^[7][8] If the diameter is adequate, these molecules can host a fullerene. For example, [10]cycloparaphenylene can host a C₆₀ fullerene.

The first carbon nanohoop was entirely made of phenylenes. Newer examples contain other aromatic repeating units.