Synthesis and characterization of new ferroelectric liquid-crystalline cyclic oligosiloxanes containing methyleneoxymethylene spacers

The synthesis of side-chain liquid-crystalline oligocyclosiloxanes containing methyleneoxymethylene spacers, two different mesogenic cores (including biphenyl phenyl carboxylate or biphenyl fluorophenyl carboxylate groups) and chiral tails is presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurements reveal liquid-crystalline properties for all of the synthesized monomers and oligomers. All cyclic oligosiloxanes exhibit enantiotropic smectic A and chiral smectic C phases. The mesogenic properties of the cyclic oligomers and side-chain liquid-crystalline precursor are discussed. (C) 2005 Society of Chemical Industry.