title: 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.
authors.affiliation: Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: J R
authors.initials: JR
authors.lastname: Magana
authors.affiliation: Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Homs
authors.affiliation: Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Solans
authors.affiliation: Division of Physical Chemistry, Lund University , Getingevägen 60, SE-22241 Lund, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Obiols-Rabasa
authors.affiliation: International Iberian Nanotechnology Laboratory , Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal.
authors.forename: L M
authors.initials: LM
authors.lastname: Salonen
authors.affiliation: International Iberian Nanotechnology Laboratory , Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal.
authors.forename: C
authors.initials: C
authors.lastname: Rodríguez-Abreu