Multivariate analysis of protolytic and tautomeric equilibria of Erythrosine B and its ester derivatives in ionic and non-ionic micelles

Protolytic Equilibria in Organized Solutions: Ionization and Tautomerism of Fluorescein Dyes and Related Indicators in Cetyltrimethylammonium Chloride Micellar Solutions at High Ionic Strength of the Bulk Phase

“…It deals about the zwitter-ion H2Z ± , quinonoid H2Q, and colorless lactone H2L. Their structures in solid state [37,58,59] and solution [13,16,17,[28][29][30]32,36,60,61] are well documented by different authors. The H2Z ± tautomer was observed mainly for fluorescein in water [7,57,61].…”

“…Along with other pK a -probes, dyes of the fluorescein series are used to understand micellar solutions and related systems [7,8,[12][13][14][15][16][17]. Their fluorescence can be used as an additional source of information on the properties of surfactant micelles [18,19].…”

“…It is of interest to study such dye + micelle systems, which are of practical importance and at the same time allow us to expand our knowledge of the properties of dyes. The most widely studied and applied are fluorescein and its halogen derivatives [14,[16][17][18][19][20][21][22][23][26][27][28][30][31][32]39]. Some new properties of nitro derivatives [15,29,37,38,46,47] and thio analogues of fluorescein [48] have been also described.…”

“…Here pK w a is the thermodynamic pK a value in water, w γ m i are the transfer activity coefficients of the corresponding species from water to the pseudophase, Ψ is the electrical potential of the Stern layer, F is the Faraday constant, R is the gas constant, and T is the absolute temperature. The pK a a values of indicators are used for evaluation of the interfacial electrical potentials of surfactant micelles and related objects [8][9][10][11][12]16,17]. The first two terms of the right-hand side are usually equated to the pK a a value of the same indicator in micelles of non-ionic surfactants, where Ψ approaches zero.…”

“…Some data characterizing the CTAC-4.00 M KCl system have already been obtained in this laboratory. Using the indicators n-decylfluorescein and N,N -di-n-octadecyl rhodamine, the Ψ value was estimated as + (15)(16) mV [8]. It means that the ΨF/2.303RT value is about 0.26 and the difference between pK a a and pK w a is caused mainly by the log(γ B /γ HB ) item.…”