Deriving binary phase diagrams for chromonic materials in water mixtures via fluorescence spectroscopy: cromolyn and water

Abstract

We report here the first example of a new and novel method of determining the binary temperature-composition phase diagram of a chromonic material in water using its intrinsic fluorescence. Disodium cromoglycate, or cromolyn, is an anti-allergy medicine representative of a class of compounds known as the chromonics. We have discovered that cromolyn's fluorescence is very sensitive to the polarity, hence structure, of the phase it exhibits. The fluorescence signal shifts its wavelength maximum and its shape depending on whether the cromolyn is a single phase or in coexisting phases. Since the signal due to individual phases can be identified, the fluorescence signal can reveal the temperature-induced transitions between single phase and phase coexistence regions. By studying such fluorescence data for different compositions, an isobaric temperature-composition phase diagram may be constructed. We present here a phase diagram derived from fluorescence studies that is in agreement with previous determinations using other techniques. Our results suggest that the binary phase diagrams of other intrinsically fluorescent chromonic materials, such as perylene monoimide and bisimide derivatives used in organic optoelectronic devices, solar cells, and light-emitting diodes, can be studied in water using an analogous fluorescence approach.

Molecular Dynamics Study of the Effect of l-Alanine Chiral Dopants on Diluted Chromonic Solutions

“…A total of four systems were simulated: a reference or control system with no added additives, and three additional ones doped with l -alanine. The control system (or system A) was modeled at 12 wt % (0.27 mol kg –1 ) DSCG/water concentration, which corresponds to the isotropic phase for the simulated temperature and pressure conditions . This concentration regime, which is located close to the isotropic–nematic transition, was carefully selected to investigate the impact of l -alanine molecules on both intra- and intercolumnar levels.…”

“…The control system (or system A) was modeled at 12 wt % (0.27 mol kg −1 ) DSCG/water concentration, which corresponds to the isotropic phase for the simulated temperature and pressure conditions. 60 This concentration regime, which is located close to the isotropic− nematic transition, was carefully selected to investigate the impact of L-alanine molecules on both intra-and intercolumnar levels. Doped systems were prepared by adding L-alanine to the control DSCG/water model using three distinct L-alanine concentrations (c Ala ), that is, 0.5, 1.0, and 2.0 wt % (systems B, C, and D, respectively), with respect to the total weight of each simulated solution.…”

Cromoglycate mesogen forms isodesmic assemblies promoted by peptides and induces aggregation of a range of proteins

“…[1][2][3][4][5][6][7][8][9][10][11] Among the different types of liquid crystals, lyotropic chromonic liquid crystals are different from conventional surfactant-based lyotropic liquid crystals as the former consist of nonamphiphilic molecules assembled in water and the assemblies further align to form LC phases. 1,[12][13][14][15][16][17][18][19][20][21][22][23][24][25] Due to the nonamphiphilic nature of the mesogen, the assembly of the molecules does not proceed with the assembly process of surfactants (conventional lyotropic liquid crystals). Instead, it is believed to proceed with an isodesmic assembly process, [13][14][15][25][26][27] which is similar to a dynamic noncovalent polymerization without a critical aggregation concentration or a nucleation process.…”

“…Many novel assembly properties have been observed for this chromonic liquid crystal. 15,17,18,20 However, it is surprising that the observation and studies for the isodesmic assembly for this class of liquid crystals are scarce, 13,14,22,24 suggesting that the concentration range for isodesmic assembly may be narrow.…”