Liquid-Crystalline Bisadducts of [60]Fullerene

摘要

A second-generation cyanobiphenyl-based dendrimer was used as a liquid-crystalline promoter to synthesize mesomorphic bisadducts of [60]fullerene.Liquid-crystalline trans-2,trans-3,and equatorial bisadducts were obtained by condensation of the liquid-crystalline promoter,which carries a carboxylic acid function,with the corresponding bisaminofullerene derivatives.A monoadduct of fullerene was also prepared for comparative purposes.All the compounds gave rise to smectic A phases.An additional mesophase,which could not be identified,was observed for the trans-2 derivative.The supramolecular organization of the monoadduct derivative is governed by steric constraints.Indeed,for efficient space filling,adequacy between the cross-sectional areas of fullerene (approx 100 A~2) and of the mesogenic groups (approx 22-25 A~2 per mesogenic group) is required.As a consequence,the monoadduct forms a bilayered smectic A phase.The supramolecular organization of the bisadducts is essentially governed by the nature and structure of the mesogenic groups and dendritic core.Therefore,the bisadducts form monolayered smectic A phases.The title compounds are promising supramolecular materials as they combine the self-organizing behavior of liquid crystals with the properties of fullerene.