Solvation statics and dynamics of coumarin 153 in dioxane-water solvent mixtures

We studied the solvation statics and dynamics of coumarin 153 dye in a dioxane-water binary solvent mixture. The solvation energy of coumarin 153, both in the ground and excited electronic states in dioxane-water mixtures, exhibits a nearly linear solvatochromic shift as a function of the polar solvent mole fraction. Part of the solvation dynamics of the dye in its excited state is rather slow and almost independent of the mixture composition. The slow solvation dynamics arose from the presence of large cosolvent oligomers due to the strong association of the two liquids rather than the dielectric enrichment or specific hydrogen bonding to the dye in these mixtures.