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A giant wheel
02 December 2014 - Organic chemistry
May, Jester and Höger report on a new giant of a molecule IN JACS (DOI). This blog has been taken an interest in chemical giants before. Here are the characteristics: it is a C1878H2682 hydrocarbon resembling a spoked hexagonal wheel. The spokes and rim consist of phenylene-ethynylene-butadiynylene units, the core is based on hexaphenylbenzene and the phenylene groups each have two dodecyl side chains that help solubility. The molecule was constructed with a combination of Sonogashira coupling reactions (a lot of palladium and copper) and protection / deprotection reactions. Final step at a 20 mg scale.
All lab techniques thrown at the new compound supported its structure: proton NMR, MALDI-MS (mass 25,350 versus 25,260 expected), GPC (low hydrodynamic volume consistent with flattened shape). In STM the hexagons really stand out and are consistent with a 12 nm diameter. Perhaps not surprisingly this giant hydrocarbon was conceived at the Kekule-Institut in Bonn.