NONCHIRAL COMPOUNDS EXHIBITING ALTERNATING TILT SMECTIC PHASES

In this article we present an investigation of the liquid crystal prop erties of nonchiral and racemic branched alkyl chain (swallow-tailed) molecules and some chiral analogues based on a cinnamic acid core grou p, It was found in these systems that increasing the extent of the bra nching of the terminal alkyl chain increased the incidence of alternat ing tilt smectic phases, whereas smectic C-alpha and smectic C-gamma p hases were suppressed. X-ray studies of the effect on the layer spacin g in the smectic A phase of increasing the long alkyl branch of one se ries of compounds are included. Results of polarisation studies on som e chiral analogues are also reported.