Effect of solvent on the quenching of fluorescence of safranine T(3,7-diamino-2,8-dimethyl-5-phenylphenazinium chloride) in binary solvent mixtures

Fluorescence quenching of 3,7-diamino-2, 8-dimethyl-5-phenylphenazinium chloride (safranine T (ST)) by halides and pseudo halides in binary solvent mixtures was investigated by steady-state fluorescence spectroscopy. Several parameters, such as dielectric constant, viscosity coefficient, ET30 and fluorescence quantum yield have been investigated as a function of solvent compositions. In mixed solvents ST has been used as a probe for studying the microheterogenity of the mixture. The preferential solvations around ST in the excited state were determined. The Stern-Volmer quenching constants at different compositions of solvent mixtures were determined and the rational analysis of the results was attempted.