V-shaped Schiff's base liquid crystals based on resorcinol: synthesis and characterisation

This paper designed and synthesised a series of V-shaped liquid crystal molecules (X-SBA(n)E) with resorcinol as the core and Schiff base as the mesogenic arms (X-SBAA(n)). The effects of polarity of terminal groups (X=-CH3O,-CH3,-Cl) and length of flexible chain (n = 4,6,8) on mesogenic ranges were discussed. The chemical structure of X-SBAA(n) and X-SBA(n)E was studied using FT-IR and H-1-NMR while their thermal behaviour and mesogenic ranges were investigated via differential scanning calorimetry (DSC) and polarising optical microscopy (POM). The results indicated that X-SBAA(n) containing OCH3 and Cl substituents exhibited mesophase except for the analogue having CH3 substituent which was found to be non-mesogenic. All of the synthesised X-SBA(n)E had liquid crystal properties and exhibited nematic phases in heating and cooling. The length of the flexible spacers and terminal groups significantly influenced their mesogenic ranges.