Distribution of oxacyanine dyes between water and nitrobenzene: Determination of the partition constants, association, and potentials of transfer of the dye cations on liquid/liquid interfaces

Abstract

Partition constants for the oxacyanine dyes between water and nitrobenzene were determined using their absorbance and fluorescence properties. From these values the standard potential of transfer for a group of oxacyanine dye cations was calculated. Several effects which can cause a variation of observed distribution ratio with dye concentration are examined. In particular, association of the dyes in the aqueous phase is determined conductometrically and is used in the correction. The effects of dye concentration and acidity of the solvent on the dye distribution ratio are also examined. The standard potential of transfer for these ions is quite negative so that the dyes are more suitable as supporting electrolytes, or must be studied on liquid/liquid interfaces without supporting electrolytes. © 1990.