Hybrid Rod-Like and Bent-Core Liquid Crystal Dimers Exhibiting Biaxial Smectic a and Nematic Phases
Journal of Materials Chemistry
Dielectric Inversion Frequency, Banana Calamitic Dimers, Mesophase Behavior, Homologous Series, Molecular Design, Polar Order, Mesogens, Transition, Field, Unit
Liquid crystal hybrid dimers involving bent-core units and rod-like units were designed, synthesized and investigated by a combination of polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction studies. All the four unsymmetrical dimers 1–4 exhibited stable nematic phases over a wide temperature range. Moreover, dimer 1exhibited the biaxial smectic A (SmA) phase and dimer 2 exhibited a highly ordered mesophase below the nematic (N) phase. Two rod-like and bent-core nematogenic units were covalently linked in dimers 3 and 4 to furnish exclusively the nematic phase. The observation of the biaxial SmA phase underlying the nematic phase in one of the bent-core–rod dimers 1 would be a significant step forward towards achieving the biaxial nematic phase and resolving controversies related to the presence of cybotactic groups.
Wang, Yan; Yoon, Hyung Guen; Bisoyi, Hari Krishna; Kumar, Satyendra; and Li, Quan (2012). Hybrid Rod-Like and Bent-Core Liquid Crystal Dimers Exhibiting Biaxial Smectic a and Nematic Phases. Journal of Materials Chemistry 22(38), 20363-20367. doi: 10.1039/c2jm34315k Retrieved from http://digitalcommons.kent.edu/phypubs/84