Synthesis and mesomorphic properties of new V-shaped shape-persistent nematogens containing a thiazole or a thiadiazole bending unit

Abstract

Two series of new V-shaped molecules, containing a central thiazole or thiadiazole bending unit have been synthesised. The design is based on shape-persistent phenylene ethynylene scaffolds that were attached stepwise with high regioselectivity to a desymmetrised iodo and bromo functionalised bent core with an apex angle of about 160°. Molecular engineering results in materials that exhibit exclusively nematic liquid crystal phases (monotropic or enantiotropic). The phase behaviour was investigated by means of polarised optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction.