Structure and liquid crystalline properties of 5-[(4′-heptoxy-4-biphenylyl)carbonyloxy]-1-pentyne

Abstract

The crystal structure and liquid crystalline properties of a biphenyl-containing acetylene, [5-[(4′-heptoxy-4-biphenylyl)carbonyloxy]-1-pentyne (A3EO7) were investigated by electron crystallography, X-ray diffraction, polarizing optical microscopy, differential scanning calorimetry, transmission electron microscopy, and atomic force microscopy. A3EO7 crystals obtained from a toluene solution adopts a monoclinic P112/m space group with unit cell parameters of a=6.25 Å, b=7.82 Å, c=46.70 Å and γ=96.7°, as determined using electron diffraction. Upon cooling from the isotropic phase, A3EO7 exhibits a smectic A phase in the temperature range 72.4–53.6°C. Further lowering of the temperature results in the formation of a smectic C phase which exhibits a strong tendency towards crystallization.