Picotube tetraanion: a novel lithiated tubular system.

Carbon nanotubes have attracted considerable attention since their discovery,[1] and have recently been the focus of intensive investigations. Studies have revealed that nanotubes exhibit extraordinary electronic properties.[2,3] Nanotubes have been shown to ignite upon exposure to short-range flashes of light,[2] and recently ultrafast carbon-nanotubebased transistors have been shown to outperform their silicon counterparts.[3] The electronic and magnetic properties of such tubes might be studied with guest atoms present inside the tube, such as in fullerenes.[4] However, standard nanotubes, as well as fullerenes, are highly insoluble in most solvents, which makes such studies rather intricate. Additionally, nanotubes are end-capped, and the insertion of atoms or cations into the tube is very difficult. The conjugated tubelike polycyclic aromatic hydrocarbon (PAH) 5,24:6,11:12,17:18,23-tetra[1,2]benzenotetrabenzo[a,e,i,m]cyclohexadecene (1), dubbed “picotube”,[5] has successfully been synthesized in gram amounts through the dimerization metathesis of tetradihydrodianthracene.[6a] Picotube 1 possesses open ends and is more soluble than standard nanotubes. In addition, its nanotube-like structure and fullerene-like ability to include endohedral atoms makes it an ideal candidate for further study. The picotube could play a role as a host molecule, by encapsulating one or more counterions upon charging, while possibly coordinating with others on the exterior. The specific orientation of such cations could also reveal information regarding the charge distribution within the molecule.