Influence of Molecular Structural Changes on the Mesomorphic Behavior of Benzylideneanilines
Since the discovery by Heilmeier, Zanoni and Barton1 that liquid crystals with negative dielectric anisotropy exhibit dynamic scattering, there has been considerable interest in this class of materials. The Schiff Bases resulting from the reaction between para-substituted anilines and para-substituted benzaldehydes have been of particular interest, especially since the report2 that N-(4-methoxybenzylidene)-4′-n-butylaniline is nematogenic at room temperature. The research reported here is the result of a detailed study of the effects of small changes in structure on the transition temperatures of benzylideneanilines. Specifically, two series of compounds (I) and (II) are described. In both series the alkoxy group is systematically varied from methoxy to heptyloxy. In series I, the alkyl groups used were n-C4H9, n-C5H11, n-C6H13, n-C7H15 and n-C8H17 while in series II, the alkyl groups were C2H5, n-C4H9, n-C6H13 and n-C8H17.
KeywordsNematic Phase Alkoxy Group Smectic Phase Mesomorphic Behavior Differential Scanning Calorimeter Mode
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