Mesophase behaviour of binary mixtures of bell-shaped and calamitic compounds

Abstract

A new bell-shaped compound, (dec-9-en-1-yl) 3,5-bis{[4'-(n-nonyloxy)biphenyl-4-carbonyl]oxy}benzoate (I), with symmetrical substitution in positions 3 and 5 of the central ring, was prepared. Although this material was not mesogenic, it exhibited low melting and freezing points and was therefore suitable as a component for mixing studies. These were carried out on a binary system composed of I and the rod-like 4-(n-octyloxy)phenyl 4-(n-hexyloxy)benzoate (II), which exhibits enantiotropic nematic, as well as monotropic SmC and SmX phases. Selected mixtures were studied by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction on non-oriented samples. It was found that the binary mixtures exhibit mesomorphic properties close to room temperature. © 2010 Taylor & Francis.