The Synthesis And Characterization Of [60]fullerene Chiral Liquid Crystals

The fullerene-containing liquid crystals have attracted great research interest due to their combination of the photophysical and electrochemical properties from C60 with the anisotropic and external field-response properties from liquid crystals. The challenge for the current reported fullerene LCs is the synthesis of high fullerene content LCs. On the other hand, reports on synthesis and properties study of chiral fullerene liquid crystals are few. We demonstrate here the design, synthesis and characterization of a new class of high [60]fullerene content chiral supramolecular liquid crystals, by using the method of supramolecular liquid crystals and the decoupling method of liquid crystal polymers, together with the introduction of chiral groups. The influence of the structure on LC properites was systematically investigated. The detailed contents are summarized as the following:(1) The chiral methanofullerene derivatives with high [60]fullerene content(58% of fulleren) were synthesized based on S-2-methyl-1-butyl alcohol, with the corresponding racemic derivatives synthesized by the same route. The π-π interactions between fullerenes and the phase separation between fullerene rigid balls to soft alkyl chains induce the molecules self-assembly to form supramolecular liquid crystals with smectic-like liquid crystalline phase. The LC to isotropic phase trasition temperature is affected by the length of the flexible spacer, while the introduction of chirality has no significant effect on the liquid crystalline properties compared to the corresponding racematic compounds.(2) A series of novel chiral and corresponding racemic [60]fullerene derivatives were sythsized based on L-alanine. These molecules can form supramolecular liquid crystals by the self-assembly of π-π interactions from fullerene moieties, the phase separation between rigid ball to soft alkyl chains and the hydrogen bond between amide groups. The introduction of hydrogen bonds here leads to the hexagonal column phase in this series of material, unlike the smectic phase formed in the former S-2-methyl-1-butyloxy based derivatives. The LC to isotropic phase transition temperature is affected by the length of the flexible spacer, while the LC lattice paremeters are different for chiral [60]fullerene materials and their corresponding racemic analogues.