A Mixed Cyclodextrin-Biphenyl Thermotropic Liquid Crystal: Synthesis, Liquid-Crystalline Properties, and Supramolecular Organization

A well-defined structure liquid crystal heptakis [6-deoxy-6-(1-H-1,2,3-triazol-4-yl)(methyl)6-(4-methoxybiphenyl-4'-yloxy) hexanoyl]beta-cyclodextrin (H6B-beta-CD) was synthesized from propargyl 6-(4-methoxybiphenyl-4'-yloxy) hexanoate (P6B) and heptakis (6-deoxy-6-azido)-beta-cyclodextrin ((N-3)(7)-beta-CD) by click reaction. The chemical structure of H6B-beta-CD was confirmed by H-1 NMR, FTIR, and MALDI-TOF MS. The thermal stability of the compound was investigated by thermogravimetric analysis (TGA). The liquid crystalline behavior was studied by differential scanning calorimetry (DSC), polarizing optical microcopy (POM), and wide-angle X-ray diffraction (WAXD) measurement. These investigations have shown that the supramolecular structure of H6B-beta-CD are consisted of a large scale ordered lamellar structure and a small scale ordered structure (SmE) at low temperature region. As the temperature increases, the small scale structure becomes disordered relatively in the first instance, from smectic E to smectic A. Then, the lamellar structure collapses and nematic phase and isotropic phase are observed in sequence. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2838-2845, 2010