Novel biaxial bilayered fluid mesophases

In a substance with a substituted chlorine on the central ring of an alkylphenyl cyanobenzoyloxybenzoate we obtain evidence in a biaxial fluid medium for anomalies of periodicity similar to those initially found in the nematic and smectic A phases of the unsubstituted series (« DBn »). From X-ray studies, microscopic observations, D.S.C. recordings and magnetic measurements, a new mesomorphic nematic-smectic A2-smectic C2-smectic? sequence is reported. In the three smectic modifications there is a liquid-like order within the layers (even at short-range) and the layer thickness is close to two molecular lengths. The lowest temperature smectic phase seems to be a new lamellar structure with well defined layers.