|As reported on in this blog back in 2009 cycloparaphenylenes have more than just one research group interested. In addition to the two groups and their efforts already mentioned (Bertozzi, Itami), a third group led by Yamago now holds the throne and the crown with an 8-cycloparaphenylene (DOI). |
At least the Itami group can now boast a crystal structure for the less impressive 12-cycloparaphenylene molecule in a new publication (Segawa et al. DOI). The synthesis has also been improved and according to note 10 Itami's method is now also the more affordable: in terms of metal catalyst costs only 6000 dollars per mole of belt (catalysis by cheap nickel) versus the 40,000 dollar per mole belt in the Yamago method (stochiometric palladium).
In the new crystal structure the rings are 150 picometer across with D3d symmetry and aligned in a herringbone pattern. The molecules are also aligned in a way that they form tubes which makes the researchers speculate host-guest chemistry opportunities or even chemically linking the hoops together in a bottom-up nanotube synthetic scheme.