Thermodynamic Characterization of the Aggregation Phenomena of Safranine‌T by Spectral Titration and Chemometric Analysis

The dimerization constants of Safranine T have been determined by studying the dependence of its absorption spectra on the temperature in the range 30–70 ◦C at different total concentrations of Safranine T (1.03×10−5, 1.44×10−5 and 1.73×10−5 M). The monomer–dimer equilibrium of Safranine T has been determined by applying MCRALS method on the absorption spectra. The quantitative analysis of the data of undefined mixtures, was carried out by simultaneous resolution of the overlapping spectral bands in the whole set of absorption spectra. In this work the dimerization constant of Safranine T has been determined by studying the dependence of absorption spectrum on temperature at different total concentrations of dye. The enthalpy and entropy of the dimerization reactions were determined from the dependence of the equilibrium constants on the temperature (van’t Hoff equation). From these results it can be inferred that the driving force of the dimerization is of enthalpic origin.