Volume 94, Nº 9 (2024)

A new route was developed for the synthesis of N-substituted derivatives of purple acid based on the condensation of methylene-active barbituric acids with the corresponding derivatives of 5-hydroxyiminobarbituric acid. 2-Thioanalogs of purple acid were obtained for the first time using a similar method. The spectral properties and hydrolytic stability of the synthesized purpurates were studied.

The heat effects of dissolution of 5,10,15,20-tetrakis(1′-methylpyrid-4-yl)porphine tetraiodide in water and aqueous KOH solution and 5,10,15,20-tetrakis(1′-carboxymethylpyrid-4-yl)porphine tetrachloride in aqueous alkali solution at a temperature of 298.15 K were measured by direct calorimetry. The values of the standard enthalpies of formation of 5,10,15,20-tetrakis(1′-methylpyrid-4-yl)porphine tetraiodide were calculated by the additive group method based on group systematics with the classification of Benson-type fragments, taking into account the influence of the primary environment of atoms.

By spectrophotometry studied the interaction of curcumin, a biologically important molecule, with tetradecyltriphenylphosphonium bromide in an aqueous environment depending on the concentration of surfactants in the premicellar and micellar ranges. Experiments were carried out with saturated solutions of curcumin under conditions of thermodynamic equilibrium of the solution with the dye precipitate. The solubility of curcumin in water has been clarified (about 2 µM). It has been shown that the process of solubilization of curcumin begins in the premicellar region of surfactants, is enhanced in the presence of adsorption protomicelles, but is most effective in the presence of ordinary micelles. The extinction coefficients of curcumin monomers in dimethyl sulfoxide, water and micellar solutions are determined. Based on experimental data, the limiting value of the solubilization capacity tetradecyltriphenylphosphonium bromide with respect to curcumin is calculated. The conductometry was used to determine the values of the critical micelle concentration (CMC) of the studied surfactant in the presence and absence of curcumin and confirm the theoretical conclusion that the CMC of the surfactants is reduced by the solubilizate.