The first solvation shell of Reichardt's dye in ionic liquids: a semiempirical study.

The nature of solvation of Reichardt's dye in ionic liquids is investigated through semiempirical calculations. We build on the basis of electrostatic considerations a cluster of three ionic pairs that represent the first solvation shell of the dye. The spatial organization of this shell is a balance between sterical, electrostatic and, in the case of functionalized ionic liquids, specific interactions. This model is not sufficient to obtain values of ET(30) quantitatively comparable to the experimental ones, but some qualitative features can be rationalized. The resulting scenario of solute-solvent interactions is different with respect to molecular solvents. Thus, we suggest caution in comparing ionic and molecular solvents through solvatochromic scales. [ABSTRACT FROM AUTHOR]