Synthesis and liquid crystalline properties of new diols containing azomethine groups

Abstract

series of new mesogenic azomethine diols were successfully synthesized by condensation reactions between various chloroalkanols and N, N′-bis(4-hydroxy)-benzylidene-o-toluidine (1). The structures of these compounds were confirmed by CHN, FT-IR, 1H-NMR, and 13C-NMR spectrophotometer. Their thermotropic liquid crystalline behavior was studied using differential scanning calorimetry (DSC) and polarizing optical microscope (POM). 4, 4′-di(4-Hydroxybutoxy)-N- benzylidine-o-tolidine (2a) does not exhibit liquid crystalline properties. A nematic texture was observed for mesogenic diols 2b, and 2d, whereas the diol 2c exhibits a smectic msophase. The increase of terminal alkyl chain in these mesogenic diols leads to a decrease in the transition temperature. © 2010 by the authors.