Effect of organized assemblies, part VIII: Spectrophotometetric study on the effect of micellar media on the pK of some substituted N-benzylideneanilines

The dissociation constants (pK values) of six N-benzylideneanilines with various substituents in 2% 1,4-dioxane-water(v/v) medium with or without aqueous micelles of ionic and nonionic surfactants have been determined spectrophotometrically. Three distinct peaks are observed for N-benzylideneanilines containing hydroxyl group and two distinct peaks for the species without hydroxyl group when the pH is varied within the pH range 1–14. The peaks are assigned to the neutral or protonated/ionized species of the corresponding N-benzylideneanilines. The pK values have been determined by observing the change in wavelength maximum (λmax) of the corresponding species as a function of pH. The pK values of the benzylideneanilines are found to be affected significantly by the substitutions as well as the environment of the ionic and nonionic micelles. The data support the presence of intramolecular H-bonding in o-hydroxy substituted N-benzylideneanilines. The localization site of N-benzylideneanilines within the organized assemblies has been established from the pK data and the structure of the organized assemblies has been suggested to be of Mengerʹs type.