Chiral calamitic mesogens with different terminal chains

Liquid crystals, which are between solid and liquid states of matter, have many application areas such as LCD?s, digital displays and sensors. Especially chiral calamitic liquid crystals have been intensively investigated in both academic and technological fields due to their applications in display devices showing fast switching behavior. Calamitic (rod-like) liquid crystals are mesogens which have a long molecular shape and in general, they are composed of rigid central core and flexible aliphatic chains. Chirality in the calamitic liquid crystal phases is usually obtained by the introduction of a chiral group to the molecular structure. Chiral group can be located to very different positions of the rod-like structure such as a central core unit, an aliphatic chain or a linking group. In recent years, fluorocarbon chains have often been used as a terminal chain. It has been observed that replacing alkyl chains which generate a mobile segment with semifluorinated groups in liquid crystal systems influences some mesomorphic properties and induces a mesophase stabilization. In this study, the design, synthesis and characterization of new calamitic mesogens combining chiral chain with semifluorinated segment in the same molecule have been carried out in order to study the impact of microsegregation and the chirality on the mesomorphism. The structures of mesogenic compounds have been characterized by using spectroscopic methods (1H-NMR and 13C-NMR). Liquid crystal properties of compounds which show chiral mesophases have been investigated by using polarization microscope (PM) and differantial scanning calorimetry (DSC). Keywords: Liquid crystals, Chiral calamitic mesogens, Semifluorinated compounds