Unusual bilayered fluid smectic modifications in polar series

Through the description of three new series of polar compounds with a cyano or a nitro terminal group we progress in the generalization of the (x, T) binary diagrams dealing with bilayered fluid smectic phases. New arguments are put forward concerning the conspicuousness of the SAd-S A2 transition according to the structure of the SAd phase. For the second time a S A2→ SC2→ S? bilayer sequence appears in which the layers remain liquid.