Synthesis and characterization of novel cholesterol based mesogenic compounds using ‘click’ chemistry

Abstract

An efficient route for the synthesis of hitherto unreported non-symmetric dimesogens consisting of a cholesteryl moiety and an aromatic mesogenic unit interconnected through a pentamethylene or decamethylene spacer by Cu(I)-catalyzed azide–alkyne cycloaddition ‘click’ chemistry has been developed. The aromatic units consist of two phenyl rings linked to a triazole moiety. A new trimesogen consisting two cholesteryl esters and an aromatic segment joined by pentamethylene spacer has also been synthesized. The newly synthesized mesogens show N*, TGB and partially bilayered SmC* (SmC_d*) phases. The liquid crystalline phases were investigated with the help of polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and powder X-ray diffraction studies. DFT study was also used to locate the orientation of the dipole at the centre position i.e. at ester linkage. All the compounds were characterized from their elemental analyses and spectral data.