Supramolecular fullerene materials: dendritic liquid-crystalline fulleropyrrolidines

[60]Fullerene-contg. liq.-cryst. dendrimers were synthesized from the first to the fourth generation by applying the 1,3-dipolar cycloaddn. reaction from a mesomorphic dendritic-type aldehyde deriv., sarcosine (N-methylglycine) or glycine and C60. The cyanobiphenyl unit was used as a liq.-cryst. promoter. With the exception of the first-generation fullerene dendrimer, which was found to be nonmesomorphic, all fullerene-based dendrimers gave rise to a smectic A phase. The liq.-cryst. fullerenes led to two different supramol. organizations within the smectic layers: for the second-generation dendrimers, the mols. are oriented in a head-to-tail fashion within the layers; for each mol. the cyanobiphenyl units point in the same direction. For the dendrimers of third and fourth generations, the dendritic core extends laterally, parallel to the layer planes; the mesogenic units are oriented above and below the dendritic core. For the aldehyde precursors, only one organization inside the layers was obtained, similar to the one obsd. for the third and fourth fullerene-based dendrimers. Cyclic voltammetry investigations displayed several one-electron and multielectron redn. processes; no significant interaction in the ground state between the fullerene and the dendrimer was noticed. The title compds. showed the typical electrochem. stability of fulleropyrrolidines. [on SciFinder(R)]