Guest-Host Systems with Anthraquinone Dyes: Thermodynamic and Structural Features

Abstract

We report on experimental and theoretical investigations concerning the solubilities of pleochroic dyes in several liquid crystalline hosts. The solubilities of five anthraquinone dyes in these hosts were measured at different temperatures in the nematic phase and for three single-component hosts also in the isotropic phase. Owing to the fact that these measurements take rather long time we especially dealt with the question whether the solubilities of the dyes can be calculated on the basis of the thermodynamic properties of the compounds. For the calculations we used an equation that assumes ideal solutions as well as another one that takes into account the interactions between the molecules. The results will be discussed also with regard to the empirical experience as far as the influence of special terminal groups on the solubility is concerned.

The structures of four anthraquinone dyes in the crystalline phase are discussed with special regard to those structural details that may affect their behaviour in guest-host systems.

Key Words:

• guest-host systems
• solubility parameters
• anthraquinone dyes
• thermodynamics
• molecular structures