Partially bilayer smectic A phase in a terminally non-polar comound

Abstract

We report the observation of a partially bilayer smectic A phase in n-dodecyl-4-( 4-ethoxybenzylidene amino)-a-methylcinnamate, a compound which does not possess a strongly polar cyano or nitro end group. The ratio of the layer spacing to molecular length is found to be about 1.12. The dielectric anisotropy versus temperature plot exhibits a reversal of sign in the smectic A phase revealing a pronounced dipole-dipole correlation in the longitudinal direc- tion. Such a sign reversal has probably been observed for the first time in a pure smectogenic material.