Mesomorphic proprieties and molecular structure. II. Structure of smetic A phase in the 4-propionyl-4-n-alkanyloxy-azobenzene series

Structural parameters concerning the smectic A phase in homologues of the 4-propionyl-4'-n-alkanoyloxy-azo-benzene series have been obtained by using dilatometry and X-ray diffraction techniques. The comparison with the data of the previously investigated homologues of the 4-acetyl-4'-n-alkanoyloxy-azo-benzene series suggests that the same model can be adopted for both series with some modifications regarding the spreading of the aliphatic chains and the tilt angle of the aromatic cores. Experimental evidence for the tilt angle of the rigid part of smectogenic molecules in the smectic A phase is discussed in relation to the chemical constitution and molecular architecture.