Phase behaviour of novel liquid crystalline mixtures based on thiobenzoates†

Abstract

Five compounds from the 4-n-pentylphenyl-4′-n-alkoxythiobenzoates homologous series, 4-chlorophenyl-4-n-octyloxythiobenzoate and two chiral compounds (S)-(+)-1-methylheptylbiphenyl-(4-n-pentylphenyl)thiobenzoate and (S)-(+)-4-(4′-n-penthylbenzoyl-thiobenzoyloxy)benzoate 1-methylheptyl have been prepared and investigated for their mesophase behaviour in new binary and ternary mixtures. The compounds and mixtures were thermally characterized by differential scanning calorimetry, polarizing optical microscopy and transmitted light intensity. Phase diagrams were constructed for various binary mixtures and one ternary mixture. The results are discussed in terms of influence of the molecular structure of the liquid crystalline components upon thermal stability of mesophases in their mixtures, and in particular the importance of terminal substituent. The existence of the nematic N, smectic A and smectic C multicritical point, the NAC point was suggested for three thioester mixtures. †Dedicated to Prof. Dr Jerzy A. Janik on his 80th birthday.