Orientational order of p-n-alkoxybenzylidene-p'-fluoroanilines. X-ray diffraction and electro-optic response of the chiral (S)-p-2-methylbutyloxy derivative

This work continues our study of the mesomorphic properties of the p-n-alkoxybenzylidene-p'-fluoroanilines. Previous studies have shown that the straight chain homologues, with the number of carbon atoms in the chain ranging from 4 to 8, form smectic phases. In this paper we describe H-2 NMR studies of the homologues with n = 4, 5 and 8 and the synthesis and properties of a chiral branched chain derivative, (S)-p-2-methylbutyloxybenzylidene-p'-fluoroaniline. This compound is not mesomorphic, but does show solid state polymorphism. From an optical, electro-optical, DSC and X-ray diffraction study we infer that the higher temperature crystalline form is a CrE phase.