The investigation of the role of structural segments on mesomorphism in 4-cyanoresorcinol based banana-shaped liquid crystals

Liquid crystals, which have the anisotropy property of the solids and the fluidity property of liquids, are used for different purposes in many technological products such as LCD (liquid crystal display), solar cells, sensors due to their orientation in electric and magnetic field. The synthesis of large number of new molecules is required to examine the new liquid crystal phase formations and their properties which may arise from new molecule designs. Banana-shaped liquid crystals that have discovered recently have a great interest due to the fact that they exhibit polar order and superstructural chirality in their mesophases and show mesophase diversity. In the design of banana-shaped molecules, the structure of central unit and substitution of polar groups, the number of aromatic rings in the rod-like units, the type and orientation of linking groups, the length of the terminal chains and chain branching, give rise to significant changes in the mesophase types and transition temperatures. In this study, the design and synthesis of new banana-shaped liquid crystals, which consist of resorcinol central unit with a cyano polar group, biphenyl based rod-like unit which is terminated by a (S)-3,7-dimethyloctyloxy chiral group at one side and a benzoate based rod-like unit carrying alkoxy terminal chains in different length at the other side, have been carried out and investigated structure-property relations. The structures of synthesized compounds were characterized by classical spectroscopic methods (1H-NMR and 13C-NMR) and elemental analysis (EA). Their mesomorphic properties were investigated by using polarised optical microscopy (PM) and differential scanning calorimetry (DSC).