Lidia Zapała

Studies on equilibrium of anthranilic acid in aqueous solutions and in two-phase systems: Aromatic solvent–water

The acid-base equilibria of anthranilic acid have been characterized in terms of macro- and microdissociation constants (dissociation constants K(a1), K(a2) and tautomeric constant K(z)). On the basis of spectrophotometric investigations the values of the distribution ratio D of anthranilic acid in the two-phase systems: aromatic solvent (benzene, ethylbenzene, toluene, chlorobenzene, bromobenzene)-aqueous solution were obtained. Employing the results of potentiometric titration in the two-phase systems: aromatic solvent-aqueous solution the distribution constant K(D) and dimerization constant K(dim) values were calculated. The influence of organic solvent polarity and pH of the aqueous phase on the contents of the particular forms of the acid in the two-phase systems were analyzed.

Studies on the distribution of N-phenylanthranilic acid in two-phase system: Aromatic solvent–water

The detailed description of equilibria of N-phenylanthranilic acid in the aqueous solutions and in the two-phase systems: aromatic solvent-aqueous solution were obtained. The isoelectric point, pH(I), the dissociation constants of the protonated form, K(a1), and the neutral form, K(a2), in the aqueous solutions were determined from the apparent ionization constant in methanol-water solutions of various proportions by extrapolation to zero co-solvent using Yasuda-Shedlovsky procedure. On the basis of the spectrophotometric investigations, the values of the distribution ratio, D, of N-phenylanthranilic acid in the two-phase systems: aromatic solvent (benzene, ethylbenzene, toluene, chlorobenzene, bromobenzene)-aqueous solution were obtained. Employing the results of the potentiometric titration in the two-phase systems: aromatic solvent-aqueous solution, and using models of singular and multistep equilibria the values of the distribution constants, K(D), dimerization constants, K(dim), were calculated. The significant influence of the polarity of the applied aromatic solvents and pH of the aqueous phase on the percentage of the particular forms of N-phenylanthranilic acid in the two-phase systems was proved.

Synthesis, spectral and thermal study of La(III), Nd(III), Sm(III), Eu(III), Gd(III) and Tb(III) complexes with mefenamic acid

New binuclear complexes of La(III), Nd(III), Sm(III), Eu(III), Gd(III) and Tb(III) ions with mefenamic acid were obtained in solid phase. For all compounds considered, complexation occurs at pH 6–6.5. The analyzed complexes were characterized on the basis of chemical and elemental analyses, molar conductance, UV–Vis, IR and 1H NMR spectroscopies as well as thermoanalytical techniques. According to the research results, the molecular formula of the complexes is Ln2(C15H14NO2)3(OH)3×nH2O, with the exception of the La(III) complex which has the formula La2(C15H14NO2)5(OH). The results show that only the carboxyl group is involved in the coordination of the rare earth ions in the bidentate mode. Coordination does not occur through the nitrogen atom. All the complexes are soluble in DMSO, and they are nonelectrolytes. The TG-FTIR technique was employed in order to study a decomposition pathway of the obtained compounds. The received results provide information on the composition, thermal stability, thermal decomposition, as well as the gaseous products that evolved during the thermal decomposition of the considered compounds.

Studies on the sorption behavior of quercetin, phenol, and caffeine as test substances on diol mixed-mode HILIC column

ABSTRACT The influence of mobile phase composition and column temperature on the retention behavior of quercetin (Q), phenol (PH), and caffeine (CAF) as test analytes on diol- Acclaim Mixed Mode HILIC-1 column in mobile phases containing varying fractions of methanol in water and acetonitrile in water was analyzed. Brief analysis of the column efficiency was also presented. Using the frontal analysis (FA) method the adsorption studies at the different mobile phase compositions were undertaken and the adsorption energy distributions (AED) have been calculated prior to selection of proper adsorption model. The calculations revealed heterogeneous interactions for Q and PH in the analyzed systems while homogeneous for CAF in systems with low water content in eluent and heterogeneous in systems with high water content. The Langmuir and bi-Langmuir isotherm turned out to be excellent in description of these adsorption trends. GRAPHICAL ABSTRACT

Synthesis, characterization and antibacterial studies of Tm(III), Yb(III) and Lu(III) complexes of morin

Abstract New solid amorphous compounds of Tm(III), Yb(III) and Lu(III) with morin have been synthesized. Their composition and some physicochemical properties have been studied by elemental analysis, thermogravimetric analysis, IR spectroscopy as well as by conductivity, UV/Vis, MS, and NMR spectroscopies in solution. The spectroscopic studies have indicated that the 3-OH hydroxyl group and the carbonyl oxygen of morin were involved in the coordination of metal ion. The antibacterial activity of the synthesized compounds has been determined by the cylinder-plate diffusion and dilution methods (determination of minimum inhibitory concentration).