Fullerene-containing liquid-crystalline dendrimers

Addition reaction of mesomorphic malonate-based dendrimers (up to the fourt h generation) with C-60 gave liquid-crystalline fullerene derivatives. The cyanobiphenyl unit was used as liquid-crystalline promoter. The malonates p resented nematic and/or smectic A phases. The fullerenes showed only smecti c A phases, with the exception of the second generation dendrimer for which smectic A and nematic phases were observed. The supramolecular organizatio n of the fullerene-based molecular units within the smectic A layers was in vestigated by X-ray diffraction. Two structural regimes were determined. Fo r the low generation dendrimers, the supramolecular organization is determi ned by steric factors. For the high generation dendrimers, the mesogenic gr oups impose a microphase organization: due to lateral extension of the bran ching part of the molecule, the cyanobiphenyl groups arrange in a parallel fashion as in classical smectic A phases, the rest of the macromolecule bei ng located between the mesogenic sublayers.