Synthesis and properties of new liquid crystalline compounds containing an alkoxyphenylazo group

In the present study, a series of Schiff bases: 5-((4-nhexadecyloxyphenyl)azo)-N-(4-nalkoxyphenyl) salicylaldimine (nalkoxy = octyloxy, dodecyloxy, hexadecyoxy) homologues have been synthesized and characterized by IR, NMR, mass spectroscopy and elemental analyses. The mesomorphic character of these compounds was studied by using differential scanning calorimetry (DSC) and polarizing microscope equipped with a heating and cooling stage. Octyloxy and dodecyloxy-containing compounds exhibit monotropic smectic A liquid crystalline behavior, but hexadecyloxy-containing compound shows enantiotropic smectic A mesophase.