Synthesis and characterization of a new supramolecular liquid crystal complex from alkyl benzoic acid, alkyloxy benzoic acid and dicarboxylic acid groups

In this thesis, binary supramolecular liquid crystal complexes of 6BA/AA, 6BA/PA, 6BA/SA, and 8OBA/AA, 8OBA/PA, 8OBA/SA were synthesized using the mesogenic compounds 4-Hexylbenzoic acid (6BA) and 4-(Octyloxy)benzoic acid (8OBA), along with the non-mesogenic compounds Adipic acid (AA), Pimelic acid (PA), and Suberic acid (SA). The thermal analyses of these complexes were conducted using DSC, and phase transition temperatures, enthalpy changes, and mesogenic properties such as the nematic range were examined. The DSC data revealed phase transitions including crystal-smectic, smectic-nematic, and nematic-isotropic transformations. The 6BA/AA complex exhibited the widest nematic range at 39.98°C. It was also observed that the phase transition temperatures and enthalpy values obtained during heating were higher than those during cooling. Analyses performed with Polarized Optical Microscopy (POM) showed that the phase transition temperatures were consistent with the DSC results. Fourier Transform Infrared Spectroscopy (FTIR) results confirmed the formation of hydrogen bonds and the preservation of intermolecular bonds within the synthesized complexes. Microstructural analyses were conducted using X-ray diffraction (XRD), and the basal spacings between molecules were calculated. It was found that the basal spacings of the complexes were within the range of the components, and these values increased with molecular length. The minimum basal spacing was calculated as 3.76 Å for the 6BA/AA complex.