Liquid-crystalline properties of dissymmetric molecules part 3: Smectic properties of 4-[2-(perfluoroalkyl) ethoxy]-substituted nitrobenzenes and benzonitriles

This paper describes the thermal properties of some homologs of 4- and 3-[2 -(perfluoroalkyl)ethoxy]-substituted nitrobenzenes and benzonitriles. Many of the homologs show notable smectic properties involving smectic A and B p hases. The smectic structures were characterized by an X-ray diffraction ex amination. The smectic A phase has a partially interdigitated bilayer arran gement where the layer spacing is 1.2-1.8 times the calculated molecular le ngth. Interestingly, some homologs show a smectic B phase with a layer spac ing of 2 times the calculated molecular length. Both fluorophilic and polar interactions are supposed to play important roles for the molecular arrang ements.