Synthesis, Characterization and Effects to Cholesteric Lyotropic Liquid Crystal Media of -ONNO Type Schiff Bases and Metal Complexes

Abstract

Lyotropic liquid crystals (LLC) are remarkable candidates in biomimetic applications, and in this respect, their interaction mechanisms with the target molecule are controversial. The study aims to create an ordered host system for biosimilar guest molecules to determine interactions. -ONNO- type tetradentate julolidine derivative, symmetric Schiff bases were synthesized with 1,2-ethandiamine and 1,4-butanediamine, and then copper complexes were obtained from Schiff bases with a cage-like structure. To characterize the synthesized compounds FT-IR, 13C and 1H-NMR and UV-vis spectroscopies were employed. Decylammonium chloride (DACl), NH4Cl, H2O and the optically active amphiphilic molecule L-alanine decyl esther (L-ADE) as a chiral dopant were utilized in the host system. The properties of lyotropic cholesteric phases and the effects of the synthesized compounds were examined using a polarized optical microscope (POM) by measuring the helical pitch as a parameter. Synthesized Schiff bases and metal complexes (2.5-20 mM) were added to the cholesteric phase whose helical pitch was measured at 110 µm without destroying anisotropic properties. The synthesized compounds caused a lengthening in helical pitch due to settled micelles on the surface or within the micelle core, leading to a change in micelle-micelle interaction. Specifically, Cu(ac)2·H2O shortened the helical pitch. © 2024 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.