Occurrence of transition between lamellar antiferroelectric and columnar ferroelectric phases in achiral seven-ring bent-core compounds derived from 5-methoxyisophthalic acid

Abstract

The synthesis and characterization of the mesophases formed by several homologues of a series of achiral seven-ring bent-core compounds that are derived from 5-methoxyisophthalic acid are described. The lower homologues show only one phase which is non-switchable. Interestingly however, many of the higher homologues exhibit two mesophases. The higher temperature phase is lamellar and shows antiferroelectric behaviour while the lower temperature phase is columnar and exhibits ferroelectric characteristics. The mesophases have been investigated using a combination of standard techniques such as differential scanning calorimetry, polarizing light optical microscopy, electro-optical methods and X-ray diffraction.