Friday, September 3, 2010

Liquid crystals based on [60] fullerene

Liquid crystals based on [60] fullerene


Over the last decade, [60] fullerene Has attracted considerable attention in materials science.Notably, Several Efforts Have Been Aimed at Producing liquid-crystalline C60-based materials for value added in the form of INcreased Processability, film formation, and self-control over assembly. Examples of C 60 derivatives Possessing a high character SC (bearing more Than Two anisotropic moieties per C 60 via polyaddition dendritic gold approach) showed a transient Either nematic, chiral nematic has, or has smectic A phase. "Gaol cells, the properties of the materials Were Mostly Dominated By The anisotropic moieties, due to dilution of the C 60 unit.As [60] fullerene can Be regarded as a versatile building block for hard dendritic systems due to ITS tunable core Valency (1 to 6) and regioselective polyaddition We Were intéressée Further to look "at its use as a template to build multicomponent supermolecule. Applying the "orthogonal transposition" described by B. Krautler And The Diederich's method of "tether directed remote functionalization" for Specifying multifunctionnalized [60] fullerenes, it would Be possible to regioselectively prepare new Three dimensionally structured molecules and Malthus new structural motives impossible to Obtain starting from Other cores SUCH've silsesquioxanes gold gold nanoparticles .
The work described "Is a first Step Towards o Attempt to Reach and to control and Ordered arrays containing [60] fullerene. Hexaaddition On The carbonated polyhedron Has Allowed the preparation, in high yield of An enantiotropic, room temperature nematic material, despite the absence of mesomorphism of the malonate side-group promoters. It Subsequent heating-cooling cycles, a stable and Reproducible behavior Took up with the reversible sequence Glass (G) 13 Nematic (N) 60 Isotropic (I).
Here, we show Specifying That the architecture of the nematic phase has hexakisadduct inducer with unusual features. The Highly symmetric [sixty] fullerene accordingly Represents a particularly versatile scaffold for the regioselective covalent assembly of a Variety of regular Three dimensionally structured molecules, Which May enlarge sacrifice part of the Existing directory of programmed molecular components for the construction of Useful Ordered materials.
Figure 1. (A) Chemical structure of hexa-adduct of [60] fullerene. (B) micrograph in polarized light (POM) obtained at 55 ° C after cooling from the isotropic.
 Figure 2. X-ray pattern obtained at 50 ° C for the hexa-adduct of C 60. Top: snapshot oriented in a magnetic field (right) and representation of the three reflections (left). Bottom: Profile 2θ. Inset: profile 2θ obtained for a distance greater film sample (328.0 mm).

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