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 1 exhibited the biaxial smectic A(SmA) phase and dimer 2 exhibited a highly ordered mesophase below the nematic (N) phase. Two rodlike 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.
Journal of Materials Chemistry
Wang, Y.; Yoon, Hyung Guen; Bisoyi, Hari Krishna; Kumar, Satyendra; Li, Q. (2012). 8. Hybrid Calamitic and Bent-core Dimeric Mesogens and Their Biaxial SmA and Nematic Phases. Journal of Materials Chemistry 22(38) 20363-20367. doi: 10.1039/c2jm34315k. Retrieved from https://oaks.kent.edu/article/8-hybrid-calamitic-and-bent-core-dimeric-mesogens-and-their-biaxial-sma-and-nematic-phases