The self-aggregation of some 7H-indolo[1,2-a]quinolinium dyes in aqueous solution

Systematically Exploring Molecular Aggregation and Its Impact on Surface Tension and Viscosity in High Concentration Solutions

The aggregation structure of dye molecules has a great influence on the properties of dye solutions, especially in high concentration. Here, the dye molecular aggregation structures were investigated systemically in aqueous solutions with high concentration using three reactive dyes (O-13, R-24:1 and R-218). O-13 showed stronger aggregation than R-24:1 and R-218. This is because of the small non-conjugate side chain and its β-linked position on the naphthalene of O-13. Compared with R-218, R-24:1 showed relatively weaker aggregation due to the good solution of R-24:1. The change of different aggregate distributions in the solutions were also investigated by splitting the absorption curves. Moreover, it is found that the surface tension of solutions can be modified by the combined effect of both aggregation and the position of the hydrophilic group, which, however, also have an effect on viscosity. This exploration will provide guidance for the study of high concentration solutions.

The application of 7H-indolo[1,2-a]quinolinium merocyanine as a new water sensor in organic solvents

Abstract

The 7H-indolo[1,2-a]quinolinium merocyanine was applied as a new water sensor in organic solvents such as ethanol, propane-1-ol, propane-2-ol, DMSO, and DMF. The spectral changes of the dye caused by the addition of increasing amount of water into an organic solvent were investigated. Based on the results, the calibration curves were found as a relation between the position of the absorption band of the dye and the water concentration ranging from about 0.05 to 11% (w/w). In case of ethanol, propane-1-ol and propane-2-ol the plots were linear, whereas in DMSO and DMF, better results were obtained with the use of a polynomial function. The method allowed to determine the water content in a fast and precise manner.

Graphical Abstract

Electronic supplementary material

The online version of this article (10.1007/s11696-017-0328-z) contains supplementary material, which is available to authorized users.