Influence of fluorine substituent on the mesomorphic properties of five-ring ester banana-shaped molecules

The synthesis and characterization of more than a hundred achiral compounds composed of banana-shaped molecules and belonging to eleven different homologous series are reported. All these symmetrical five-ring compounds are esters and are derived from resorcinol. The compounds have been systematically substituted by fluorine on the phenyl rings of the arms of these banana-shaped molecules. The mesophases exhibited by these compounds have been characterized using a combination of polarized light optical microscopy, differential scanning calorimetry and X-ray diffraction studies. Electro-optical investigations have been carried out on several compounds and both ferroelectric and antiferroelectric properties are observed. The influence of the position of the fluorine substituent on the nature of the mesophase obtained has been examined.