Nonlinear architecture liquid crystalline materials of supramolecular 1:1 H-bonded complexes (I/II and I/III) were prepared through a self-assembly intermolecular interaction between azopyridine (I) and 4-n-alkoxybenzoic acid (II) as well as 4-n-alkoxyphenylazo benzoic acid (III). The H-bond formation of the prepared supramolecular hydrogen bonded (SMHB) complexes was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Optical and mesomorphic behaviors of the prepared complexes were studied by polarized optical microscopy (POM) as well as DSC. Theoretical calculations were performed by the density functional theory (DFT) and used to predict the molecular geometries of the synthesized complexes, and the results were used to explain the experimental mesomorphic and optical properties in terms of their estimated thermal parameters. Ordinary and extraordinary refractive indices as well as birefringence at different temperatures were investigated for each sample using an Abbe refractometer and modified spectrophotometer techniques. Microscopic and macroscopic order parameters were calculated for individual compounds and their supramolecular complexes.

Phase transition temperature and optical properties of the special oriented fluorine atoms in difluorophenylazophenyl Benzoate Thermotropic Liquid Crystal nominated (III) were studied and measured. Absorbance and transmittance in the visible region at room temperature for the compound III dissolved in methylene chloride of different concentrations were determined. The maximum absorbance for the compound III was in the blue region (447 nm) and the molar absorption coefficient was found to be 0.93 (L. mMol⁻¹.cm⁻¹). The transition temperature was determined for the thermotropic LC compound III by using DSC, POM and modified spectrophotometer techniques. Nematic and smectic phases during the cooling process were observed. Ordinary and extraordinary refractive indices, birefringence, order parameter and the molecular polarizability were determined with different temperatures for the LC phases of compound III.