Investigation of the effect of schiff base and hydrochloric acid concentration on helical pitch length in micellar induced cholesteric disc phase

The importance of liquid crystals has been increasing since the end of the 20th century, and their research is given importance. Liquid crystals are actively used in drug delivery systems, creams, cosmetics and other fields. Schiff bases are substances that are important in many fields, including pharmaceuticals, medicine, biological systems, cosmetics, agriculture, colour creation, the plastics and aerospace industries, liquid crystals, and electronics and analytical chemistry. In our study, Schiff base (Z)-4-methyl-2-(((3-nitrophenyl)imino)methyl)phenol was synthesized by using 2-hydroxy-5-methyl benzaldehyde and 3-nitroaniline The structure of the synthesized compound was elucidated using FT-IR, UV-Vis., 1H-NMR, 13C-NMR techniques. The crystallographic and molecular structure of the single crystal prepared compound was determined by X-ray technique. First, the nematic discotic phase was prepared using octyl ammonium chloride (OACl), ammonium chloride (NH4Cl) and water (H2O). Then induced cholesteric discotic phase has been obtained with the adding of sucrose. The pitch of obtained phase was measured by polarized optical microscope technique. Hexanol, octanol and decanol (C6-C8-C10) mediums were used because the Schiff base compound was insoluble in liquid crystal medium. When hexanol, octanol and decanol were added, it was observed that the structure of the helices was disrupted in the induced cholesteric disc phases. Then, alkanol solutions containing Schiff base were prepared and added to the liquid crystal systems. In systems with Schiff base + alkanol, it has been determined that the helical pitch length gets shorter as the hydrophobic part gets longer. Finally, solutions of hydrochloric acid at 1×10-7 M and 1×10-3 M concentrations were added to the above systems and the results were followed. Accordingly, as the concentration of the acid and the length of the hydrophobic part increased, the fluidity increases and the pitch shortens.