Synthesis and liquid crystal properties of new banana-shaped cinnamoyl derivatives

Three new achiral five-ring banana-shaped homologous series have been synthesized and their liquid crystalline properties studied by polarizing microscopy, differential scanning calorimetry, and electro-otpical analysis. The compounds consist of two identical mesogenic structures of bis (alkoxycinnamoyloxybenzoates) linked on a different central ring (unsubstituted or methyl-substituted). The length of the terminal alkoxy groups was varied from heptyloxy to dodecyloxy; the hexadecyloxy group was also included in the study. It was found that the polymorphism of compounds can be strongly dependent upon molecular structure in this class of compound. In particular, substituents on the central ring may exert a significant effect on the type of mesophase observed.