Self-Assembly and Formation of Chromonic Liquid Crystals from the Dyes Quinaldine Red Acetate and Pyronin Y

Abstract

The aqueous self-assembly behavior of the dyes Quinaldine red acetate and Pyronin Y in a wide range of concentrations is reported here for the first time. (1)H NMR spectroscopy, polarized-light optical microscopy, and small and wide X-ray scattering were used to get insight into molecular interactions, phase boundaries and aggregate structure. Quinaldine red acetate and Pyronin Y self-organize into unimolecular stacks driven by attractive aromatic interactions. At high concentrations, spatial correlation among the molecular stacks gives rise to nematic liquid crystals in both systems. Quinaldine red acetate additionally produces a rare chromonic O phase built of columnar aggregates with anisotropic cross-section ordered in a rectangular lattice. The O phase changes into a columnar lamellar structure as a result of a temperature-induced phase transition. Results open the possibility of finding chromonic liquid crystals in other commercially available dyes with a similar molecular structure. This would eventually expand the availability of these unique soft materials and thus introduce new applications for marketed dyes.

Anisotropic, porous hydrogels templated by lyotropic chromonic liquid crystals

“…At À18 1C, the homogeneous nematic texture is lost, and a texture associated with the O-phase is observed. 30,31,34,49 This O-phase texture also exhibits changes in brightness when rotated between crossed polarizers, indicating potential alignment of this phase (Fig. 2E).…”

Bioinspired Scaffolding by Supramolecular Amines Allows the Formation of One‐ and Two‐Dimensional Silica Superstructures

“…These are flat aromatic dye molecules that self‐assemble in water to produce hollow tubes or fibers (Scheme 1). [29–31] Due to electrostatic repulsion, charged amines moieties are positioned to the outside of the tubes/fiber, where counterions predominantly reside. This yields a one‐dimensional, supramolecular polyamine reminiscent of the covalent polyamines which guide biomineralization processes in diatoms and sea sponges.…”

Chromonic self-assemblies in a series of dialkyl-thiacarbocyanine dyes and generalization of a facile route for the synthesis of fluorescent nanostructured silica fibers

“…Previously, we reported for the first time chromonic liquid crystals formed by different cationic dyes. [15][16][17] Cyanine dyes were found to serve as templates for the preparation of mesoporous silica fibers. Evidence suggests that the anionic oligomeric silica species are bound to the cationic surface of the cyanine aggregates partially neutralizing the interaggregate long-range repulsions, causing chromonic-silicate fibers to precipitate.…”

“…Nonetheless, other cationic chromonic dyes, such as Quinaldine Red or Pyronin Y were unable to template silica, showing that the formation of cationic aggregates is not enough. [17] Fibers obtained from cationic dyes were non-fluorescent, indicating that the adsorbed dye is in the aggregated state.…”