Mesogenic benzothiazole derivatives with methoxy substituents

Two new mesogenic homologous series containing 6-methoxybenzothiazole ring at the terminus of the molecule, viz. 2-(4′-n-alkoxyphenylazo)-6-methoxybenzothiazoles and 2-[4′-(4″-n-alkoxy-benzoyloxy) phenylazo]-6-methoxybenzothiazoles were synthesized. In series I,n-butyloxy to n-tetradecyloxy derivatives exhibit nematic mesophase. Smectic A mesophase commences from then-dodecyl-oxy derivative as a monotropic phase and is retained up to the last member synthesized. All the members of series II exhibit enantiotropic nematic mesophase. The mesomorphic properties of the present series are compared with other structurally related series to evaluate the effect of the benzothiazole ring and the methoxy substituent on mesomorphism. This paper was presented at the 10th National Conference on Liquid Crystals held at Bangalore during 9–11 October 2003