Photophysical studies of xanthene dye in alkanols and in presence of inorganic ions

Eosin Y belongs to a xanthene group. It is an anionic fluorescent dye. The absorbance and fluorescence of Eosin Y have been investigated in a series of alkanols (methanol to propanol). When the solvents are added to the aqueous solution of Eosin Y (EY) the absorbance and fluorescence intensity are enhanced. The alkanols are found to affect the absorption and fluorescence spectra of the dye. On the basis of solvent adsorption model the binding constants of the dye with alkanols have been estimated. The interaction of solvent molecule with dye in aqueous solution is specific in nature. The fluorescence quenching of Eosin Y by the inorganic ions [Fe(CN)₆]⁻³, [Fe(CN)₆]⁻⁴ and Cl⁻ was also observed. The ions influenced the quenching process to different extents. The rate constants of quenching were calculated using the Stern-Volmer equation. The equilibrium constant of dye in presence of inorganic ions are determined by Scott equation.