SYNTHESIS AND MESOMORPHIC STUDIES ON LIQUID CRYSTALS WITH FLUORINATED PYRROLE，AND PYRROLIDINE

Three series of new fluorinated N-heterocycles liquid crystals were synthesized from the fluorinated block 3-fluoro-4-(pyrrolidin-1-yl)phenol (3-4H), 3-fluoro-4-(3,3,4,4- tetrafluoropyrrolidin-1-yl)phenol (3-4F) and 4-(3,4-difluoro-1H-pyrrol-1-yl)-3-fluorophenol (3-2F). Their mesogenic behavior was investigated with differential scanning calorimetry (DSC) and polarized optical microscopy (POM).The results showed that the 3,4-difluoropyrrole derivatives are more conductive to the formation and stability of a liquid crystal phase than the pyrrolidine or 3,3,4,4-tetrafluoropyrrolidine derivatives. The results of DSC, POM also show that 3,4-difluoropyrrole derivatives exihibit high clearing point and a broad temperature range of nematic phases. Compounds have a wide nematic phase and a high clearing point when we combine 3,4-difluoropyrrole as the terminal group and dicyclohexyl liquid crystal building block. The physical and chemical properties of the liquid crystal molecules can be adjusted by varying the type of N-heterocycles, introducing fluorine atoms and changing the length of terminal alkyl chain.