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Two series of new Schiff base compounds were synthesized. For Schiff base compounds with a pyridine nitrogen atom in 4-position (7a–e), their supramolecular hydrogen bonding complexes show good liquid crystal properties. However, no liquid crystal property is observed for8a–e. Results of theoretical calculations demonstrate that it is the intermolecular hydrogen bond of Schiff base compounds (8a–e) that prevents the formation of supramolecular hydrogen bonding. The Schiff base compounds, with terminal alkoxy chains, can recognize Cu2+selectively with a color change. Nevertheless, others cannot recognize Cu2+. [ABSTRACT FROM AUTHOR]

Abstract: Two new Schiff base compounds, tailed by the fluoroalkoxy, were synthesized in a three-step process. Those supramolecular structures constructed by hydrogen bonding show good liquid crystal properties with higher clear points and wider mesomorphic phase ranges than other analogs containing a terminal alkoxy chain. Investigation of the optical textures by polarizing microscopy reveals that terminal fluorinated substituents convert the nematic phase of supramolecular hydrogen-bonding complexes with terminal alkoxy chains into the smectic A phase of those with terminal fluoroalkoxy chains. [Copyright &y& Elsevier]