Institut de Chimie , Université de Neuchâtel , Avenue de Bellevaux 51 , 2000 Neuchâtel , Switzerland.
Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 , CNRS-Université de Strasbourg , 23 rue du Loess, BP43 , 67034 CEDEX 2 Strasbourg , France.
J Org Chem. 2018 Mar 16;83(6):3208-3219. doi: 10.1021/acs.joc.8b00093. Epub 2018 Mar 1.
Liquid-crystalline tris[60]fullerodendrimers based on first- and second-generation poly(arylester)dendrons carrying cyanobiphenyl mesogens were synthesized for the first time by the olefin cross-metathesis reaction between type I (terminal) and type II (α,β-unsaturated carbonyl) olefinic precursors, using a second-generation Grubbs or Hoveyda-Grubbs catalyst. The modular synthetic approach developed here also allowed the selective preparation of the [60]fullerene-free, mono[60]fullerodendrimer, and bis[60]fullerodendrimer derivatives from the appropriate precursors. As revealed by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering, all of the materials displayed liquid-crystalline properties. In agreement with the nature of the dendritic building blocks, the emergence of lamellar mesophases (smectic C and/or smectic A phases), with the segregation of the various constitutive parts, was systematically observed. The small variation of the mesomorphic temperature range and of the mesophase stability suggested that the mesomorphism is essentially dominated by the dendrimer itself and is regulated by a subtle adaptive mechanism, in which the proportion of monolayering and bilayering arrangements of the multisegregated lamellar mesophases is modified in order to compensate the space requirements of each of the elementary building blocks, namely, the [60]fullerene units, the cyanobiphenyl mesogens, and the dendritic matrix.
首次通过烯烃交叉复分解反应，使用第二代 Grubbs 或 Hoveyda-Grubbs 催化剂，合成了基于第一代和第二代聚（芳基酯）树枝状大分子的基于液晶的三[60]富勒烯，这些树枝状大分子带有氰基联苯介晶基元。这里开发的模块化合成方法还允许从适当的前体中选择性制备无[60]富勒烯的单[60]富勒烯树枝状大分子和双[60]富勒烯树枝状大分子衍生物。偏振光显微镜、差示扫描量热法和小角 X 射线散射表明，所有材料均具有液晶性质。与树枝状大分子构建块的性质一致，系统地观察到层状中间相（近晶 C 和/或近晶 A 相）的出现，以及各种组成部分的分离。中间相温度范围和中间相稳定性的微小变化表明，中间相主要由树枝状大分子本身控制，并受微妙的自适应机制调节，其中多分离层状中间相的单层和双层排列的比例进行修改，以补偿每个基本构建块的空间需求，即[60]富勒烯单元、氰基联苯介晶基元和树枝状基质。
