No abstract

Addition of liquid-crystalline dendrimers onto [60]fullerene led to thermotropic liquid crystals which displayed various types of mesophases, including chiral nematic, smectic B, smectic A and columnar phases. This approach represents an interesting way for the design of self-organized structures based on [60]fullerene, and opens the way to optoelectronic applications for this carbon allotrope, such as for the development of photovoltaic devices and molecular switches.

Addition reaction of mesomorphic malonate-based dendrimers (up to the fourth generation) with C 60 gave liquid-crystalline fullerene derivatives. The cyanobiphenyl unit was used as liquid-crystalline promoter. The malonates presented nematic and/or smectic A phases. The fullerenes showed only smectic A phases, with the exception of the second generation dendrimer for which smectic A and nematic phases were observed. The supramolecular organization of the fullerene-based molecular units within the smectic A layers was investigated by X-ray diffraction. Two structural regimes were determined. For the low generation dendrimers, the supramolecular organization is determined by steric factors. For the high generation dendrimers, the mesogenic groups impose a microphase organization: due to lateral extension of the branching part of the molecule, the cyanobiphenyl groups arrange in a parallel fashion as in classical smectic A phases, the rest of the macromolecule being located between the mesogenic sublayers.{Basis of a presentation given at Materials Discussion No. 4,[11][12][13][14]