Synthesis and Mesomorphic Properties of Novel Crown Ether Schiff Bases

Abstract

Different crown ether Schiff bases were prepared by condensing a different aldehyde with trans-diamino dibenzo 18-crown-6. The physical properties as well as the chemical formulations of these compounds were derived from microanalysis and spectroscopic methods. Phase transition temperatures and the thermal parameters were obtained from differential scanning calorimetry (DSC). The texture observation was performed under polarizing optical microscopy (POM) attached with a hot stage. Most of the compounds are thermotropic liquid crystals. Different phases such as smectic, (SmC, SmA) and nematic (N) were shown by crown ether Schiff bases containing azomethine and hydroxy group which are characteristic of rodlike liquid crystals.

Keywords:

• dibenzo 18-crown-6
• liquid crystal crown ether (LCCE) Schiff base
• nematic
• smectic
• thermotropic liquid crystal

Notes

*cp = clearing point.

Cr - crystal; SmA - smectic A; SmC - smectic C; I - isotropic.