Functionalized hexa-peri-hexabenzocoronenes:: Stable supramolecular order by polymerization in the discotic mesophase

The synthesis and mesomorphic properties of hexa-peri-hexabenzocoronene (HBC) substituted with terminally functionalized n-alkyl chains are reported. Mono- and bisfunctionalized derivatives are accessible via Hagihara-Sonogashira coupling of bromosubstituted HBC derivatives and functionalized alkynes. Hexasubstituted hexa-peri-hexabenzocoronene derivatives are obtained using a cobalt octacarbonyl catalyzed cyclotrimerization of suitably substituted diphenylacetylenes, followed by an oxidative cyclodehydrogenation with iron(III) chloride dissolved in nitromethane. Thermal polymerization of HBC derivatives containing acryloyl or methacryloyl functions at the terminal position of the alkyl chains has been achieved in the liquid crystalline phase. Thereby, a network is obtained in which the Col(ho) superstructure of the liquid crystalline phase is preserved and appears to be stable between -100 degrees C and 300 degrees C.