Alignment of a Perylene-Based Ionic Self-Assembly Complex in Thermotropic and Lyotropic Liquid-Crystalline Phases

The thermotropic and lyotropic liquid‐crystalline (LC) phases of the ionic self‐assembled complex N,N′,‐bis(2‐(trimethylammonium)ethylene)‐perylene‐3,4,9,10‐tetracarboxyldiimide‐bis(2‐ethylhexyl)sulfosuccinate have been studied using polarizing microscopy, differential scanning calorimetry (DSC), and X‐ray scattering techniques. A two‐dimensional (2D) columnar thermotropic LC phase with π–π stacking of the perylene tectonic units and a lyotropic LC phase in dimethyl sulfoxide (DMSO) have been found. Different techniques have been applied to align both systems and included: surface interactions, electric and magnetic fields, shear force, and controlled domain formation at the LC–isotropic phase‐transition front (PTF). Characterization of the alignment in films has been performed using polarized UV‐vis spectroscopy and transmission null‐ellipsometry. The best results have been obtained for alignment of the material in a lyotropic phase by controlled domain formation at the PTF of the LC–isotropic phase transition. In this case, a dichroic ratio of 18 is achieved with packing of columns of perylenediimide tectons perpendicular to the PTF. Thermotropic and lyotropic liquid‐crystalline (LC) phases of the ionic self‐assembled complex of perylene‐based tectons and bis(2‐ethylhexyl)sulfosuccinate have been prepared. Alignment by controlled domain formation at the phase‐transition front (PTF) of the lyotropic LC–isotropic phase transition yielded a dichroic ratio of 18 and packing of columns of perylenediimide tectons perpendicular to the PTF (see Figure).