AM1 method

Association of 5,5′-Dibromo-o-Cresolsulfonphthalein Anions with Dye Cations in Aqueous Solution

The formation of associates in aqueous solutions between single- or double-charged anions of 5,5′-dibromo-o-cresolsulfonphthaleine and single-charged cations of cyanine dyes (quinaldine blue, quinaldine red) has been considered. Based on the spectrophotometric data, the equilibrium constants of the association were analyzed. The energy of cation-anion interactions (standard enthalpy of formation of ions and associates) was determined by the semi-empirical AM1 method and probable structures of associates were set.