Liquid‐Crystalline Bisadducts of [60]Fullerene.

Abstract

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 (∼100 Å 2 ) and of the mesogenic groups (∼22-25 Å 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.

Recent Advances in the Synthesis, Characterization, and Applications of Fulleropyrrolidines

“…The synthesis, characterization, properties, and supramolecular organization of liquid-crystalline fullerene bisadducts and monoadduct (Figure ) used as reference compound were reported in ref . The authors postulated that the mono- and bisadducts formed bilayered and monolayered smectic A phases, respectively.…”

Supramolecular Purification and Regioselective Functionalization of Fullerenes and Endohedral Metallofullerenes

“…On the other hand, several pure-isomer Prato bis-adducts condensated with liquid-crystal promoters were also organized into a mono-layered smectic A phase (Figure 34). 138 These and other examples demonstrate that judicious poly-additions of mesogenic molecules is a method of choice to control the C 60 aggregation tendency. The control of the number of additions and grafting regio-positions are essential to govern the mesogen orientations and directionalities, and thus the supramolecular organizations into various mesophases to impact directly into the physical properties of the materials.…”