Synthesis and mesomorphic properties of novel high birefringence azobenzene liquid crystals with lateral fluorosubstituent

In order to obtain liquid crystals with high birefringence (Delta n), four azobenzene compounds based on lateral fluorinated bistolane moieties with trifluoromethyl terminal groups were synthesized with Hagihara-Sonogashira cross- coupling reaction. The molecular structures of the compounds were confirmed by Fourier transform infrared, H-1-nuclear magnetic resonance. The transition temperatures, optical textures, and optical anisotropies were determined by differential scanning calorimetry, polarizing optical microscopy. The effect of the alkyl substituents on liquid crystal behavior is discussed in detail. The compounds have showed higher birefringence values.National Natural Science Foundation of China [51673157]SCI(E)ARTICLE17-1265