| Abstract
| - Janus-type liquid−crystalline fullerodendrimers were synthesized via the 1,3-dipolar cycloaddtitionof two mesomorphic dendrons and C60. By assembling poly(aryl ester) dendrons functionalized withcyanobiphenyl groups, displaying lamellar mesomorphism, with poly(benzyl ether) dendrons carrying alkylchains, which display columnar mesomorphism, we could tailor by design the liquid−crystalline propertiesof the title compounds as a function of each dendron size. The liquid−crystalline properties were examinedby polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction. Depending on thedendrimer generations, smectic (SmC and/or SmA phases) or columnar (Colr-c2mm or Colr-p2gg phases)mesomorphism was obtained. The supramolecular organization is governed by (1) the adequacy of thecross-sectional area of the dendrons, (2) the microsegregation of the dendrimer, (3) the deformation of thedendritic core, and (4) the dipolar interactions between the cyanobiphenyl groups. Comparison of themesomorphic properties of two fullerodendrimers with those of model compounds (fullerene-free analogues)indicated that the C60 unit does not influence the type of mesophase that is formed. Molecular propertiesdetermined in solution (permanent dipole moment, specific dielectric polarization, molar Kerr constant)confirm that microsegregation persists in solution and strengthen the models proposed for the structure ofthe mesophases.
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