Synthesis and mesophase behavior of mesogens bearing omega,alpha,alpha-trihydroperfluoroalkoxy end tails

One series of two-ring and two series of three-ring liquid crystal compound s, all containing omega,alpha,alpha-trihydroperfluoroalkoxy terminal tails, were prepared and characterized by IR, NMR, MS and elemental analysis. The ir phase transition behaviour was investigated by DSC and polarizing optica l microscopy. Biphenylene derivatives with the omega,alpha,alpha-trihydrope rfluoroalkoxy end group form a stable smectic A phase. In the three-ring sy stem, biphenylene ester compounds exhibit a smectic phase without a nematic phase. The compounds exhibit smectic A and smectic C phases when the termi nal groups are intermediate length alkyl and fluorinated alkyl chains. Meso gens with fluorinated tails have a broader smectic C phase than the non-flu orinated mesogens.