Ion-Pairing Chromonic Liquid Crystals via Alternately Stacked Assembly of Amphiphilic Charged π-Electronic Systems

In this study, a new assembly strategy for lyotropic chromonic liquid crystals (LCLCs) is proposed using ⁱπ-ⁱπ interactions, mainly comprising electrostatic and dispersion forces, between charged π-electronic systems to form stacking structures supported by the hydration of triethylene glycol (TEG) units. The meso-TEG-aryl-substituted porphyrin Au^III complex, an amphiphilic π-electronic cation, showed diverse states and assembly modes in ion pairs depending on the coexisting counteranions. The PCCp^- ion pair formed a hexagonal columnar (Col_h) LC phase based on a charge-by-charge assembly, suggesting the formation of an ordered arrangement of charged π-electronic systems through ⁱπ-ⁱπ interactions, with reduced interactions between the TEG chains. Furthermore, in the presence of water, LCLC behavior in the Col_h and nematic columnar phases according to the amount of water were observed for the PCCp^- ion pair as a result of ⁱπ-ⁱπ interactions. Magnetic-field-induced orientation of the charge-by-charge columnar structures upon dehydration was observed. Furthermore, single-stranded charge-by-charge columnar structures, as components of the LCLCs, were observed using transmission electron microscopy (TEM).