Thermal and dielectric studies of self-assembly systems formed by hydroquinone and alkyloxy benzoic acids

Self-assembly systems formed by hydroquinone and alkyloxy benzoic acids are isolated and characterized. Hydroquinone formed double hydrogen bonds with p-n-alkyloxy benzoic acids. Various hydrogen bonded complexes have been synthesized with hydroquinone and pentyloxy to dodecyloxy benzoic acid, respectively. FTIR studies confirm the hydrogen bond formation in the complex. Polarizing Optical Microscopic (POM) studies revealed the textural information while the transition and enthalpy values are experimentally deduced from Differential Scanning Calorimetry (DSC) studies. Phase diagram has been constructed from the POM and DSC data. The members of the present homologous complexes are characterized by POM, DSC, optical tilt angle and dielectric studies. Odd–even effect has been evinced in enthalpy values and transition temperatures corresponding to the isotropic to nematic phase transition. Optical tilt angle in Smectic C phase data has been fitted to a power law and it has been observed that the temperature variation of the tilt angle follows Mean Field theory prediction. Results of Fourier Transform Infrared Spectra (FTIR), POM, DSC, tilt angle and dielectric studies are discussed.

Research highlights
► A novel double hydrogen bonded liquid crystal homologous series has been characterized.
► HQ+6OBA and HQ+8OBA exhibit an anomalous dielectric relaxation behavior.
► An interesting observation is the detection of odd–even effect.