The effect of intermolecular actions on the mesomorphic properties of alkenoxy biphenyl-based liquid crystals

Two series of alkenoxy-biphenyl compounds have been synthesized and characterized for investigating the relationship between intermolecular actions ( e.g. , π-π stacking, dipole-dipole interactions, and van der Waals interactions) and the mesomorphic properties. Firstly, their mesophases were determined by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (XRD). Then, Density Functional Theory (DFT) calculations, UV absorption spectra and fluorescence (FL) emission spectra were also conducted to assist in analyzing their mesomorphic properties. The results show that the type and stability of liquid crystal mesophases are dependent on the intermolecular actions. Moreover, suitably modifying intermolecular actions by the terminal groups has been proved to be an effective approach to regulate the formation and stability of nematic/smectic mesophases.