Structure of the Smectic A Mesophase of the N-Oxides of Certain 4-(4′-n-Alkoxyphenyl)Pyridines

Abstract

The structure of the smectic A mesophase formed by the N-oxides of two 4-(4′-n-alkoxyphenyl)pyridines has been studied by X-ray diffraction. The thickness of the layers was found to be intermediate between one and two molecular lengths. This result has been interpreted within the framework of a model proposed recently to describe the behavior of partially bilayered smectic A phases of highly polar and dissymmetric mesogens and the degree of head-to-head association of the molecules found to be larger for the N-oxides than that determined for cyanobiphenyls.