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 phases. The smectic structures were characterized by an X-ray diffraction examination. The smectic A phase has a partially interdigitated bilayer arrangement where the layer spacing is 1.2—1.8 times the calculated molecular length. Interestingly, some homologs show a smectic B phase with a layer spacing of 2 times the calculated molecular length. Both fluorophilic and polar interactions are supposed to play important roles for the molecular arrangements.