Synthesis and mesomorphic properties of fluoro-containing azobenzene liquid crystals

Four series of azobenzene liquid crystal compounds containing a fluorinated tolan unit have been synthesized. The mesomorphic behaviours of these comp ounds were characterized by differential scanning calorimetry and optical p olarizing microscopy. The compounds of these series exhibit a nematic, a sm ectic C or a smectic B phase. This investigation revealed that the alkoxy c hain at the side of the azobenzene moiety plays a more important role in th e formation of smectic phases than the one at the side of the tolan moiety.