S. N. Gridchin

Stability Constants of Cu(II) Hydroxypropylenediaminetetraacetates

Equilibrium of complexation between 2-hydroxypropylene-1,3-diamine-N,N,N′,N′-tetraethanoic acid (H4L) and Сu2+ ions was studied by potentiometric and spectrophotometric methods. Stability constants of CuL2– and CuHL– complexes were determined at 298.15 K and I = 0.5 М (KNO3).

Potentiometric determination of the ionization constants of ethylenediamine-N,N′-diglutaric acid at 298.15 K

Step ionization constants of ethylenediamine-N,N′-diglutaric acid at 298.15 K and ionic strength values of 0.1, 0.5, and 1.0 (KNO3) are determined by means of potentiometry. The resulting data are extrapolated to zero ionic strength using an equation with one individual parameter, and the thermodynamic ionization constants are calculated. A correlation is made between the obtained results and the corresponding data for related compounds.

Thermodynamics of L-valine complex formation with Cu2+ ions in an aqueous solution

Heat effects of mixing of aqueous solutions of Cu(NO3)2 and L-valine were measured by the calorimetric method at 298.15 K and a ionic strength of 0.5–1.5 (KNO3). The standard heat effects of formation of the Cu(II) complexes with L-valine in an aqueous solution were obtained by the extrapolation to the zero ionic strength using the equation with one individual parameter. The standard thermodynamic characteristics of complex formation in the Cu2+-L-valine system were calculated.

Thermodynamics of cobalt(II) complexation with trimethylenediamine-N,N,N′,N′-tetraethanoic acid

The stability constants of cobalt(II) trimethylenediaminetetraacetates at 298.15 K and I = 0.1, 0.5, and 1.0 (KNO3) are determined by the potentiometric titration method. The heat effects of formation of the cobalt(II) complexonate at 298.15 K and I = 0.1, 0.5, and 0.1 (KNO3) are measured by the direct calorimetric method. The standard thermodynamic characteristics of the reactions under study are calculated. The results obtained are compared with the corresponding data for related compounds.

Thermodynamics of the complexation between the Cu2+ Ion and L-aspartic acid in aqueous solution

The enthalpies of complexation between L-aspartic acid (H2Asp) and the Cu2+ ion at 298.15 K and I = 0.5, 0.75, and 1.0 (KNO3) were determined from calorimetric data. The thermodynamic characteristics of the formation of the complexes CuAsp and CuAsp22− were calculated for fixed and zero ionic strengths.

Thermodynamic characteristics of protolytic equilibria of hexamethylenediamine-N,N,N′,N′-tetraacetic acid

The heats of dissociation of betaine groups of hexamethylenediamine-N,N,N′,N′-tetraacetic acid (H4L) at 298.15 K and the ionic strengths of 0.1, 0.5, and 1.0 (KNO3) were determined by direct calorimetry. The standard thermodynamic characteristics of the ptotolytic equilidria of H4L were calculated using the results from thermochemical and potentiometric measurements made under identical test conditions.

The enthalpies and dissociation constants of L-homoserine in aqueous solutions of KNO3

Acid-base interactions in solutions of L-homoserine were studied potentiometrically and calorimetrically. The constants and heat effects of the step dissociation of the amino acid at 298.15 K and ionic strengths of 0.1, 0.3, 0.5, and 1.0 (KNO3) were determined. The standard thermodynamic characteristics of the equilibria studied were calculated.

The enthalpies of solution of VOCl3 in dilute solutions of sodium hydroxide and the standard enthalpy of formation of liquid VOCl3

The enthalpies of solution of liquid vanadium oxytrichloride in dilute solutions of sodium hydroxide were determined by direct calorimetric measurements at 298.15 K and ionic strength values I = 0.3, 0.5, and 1.0 (NaClO4). The experimental data were used to calculate the standard enthalpy of formation of liquid VOCl3.

Thermochemical study of processes of complex formation of Cu2+ ions with L-glutamine in aqueous solutions

Heats of the interaction of Cu(NO3)2 solutions with L-glutamine solutions were measured directly by calorimetry at a temperature of 298.15 K and ionic strength values of 0.5, 1.0, and 1.5 (KNO3). Using RRSU universal software, the experimental data were subjected to rigorous mathematical treatment with allowances made for several concurrent processes in the system. The heats of formation of the CuL+ and CuL2 complexes were calculated from the calorimetric measurements. The standard heats of the complex formation of Cu2+ with L-glutamine were obtained by extrapolation to zero ionic strength. The complete thermodynamic characteristic (ΔrHo, ΔrGo, ΔrSo) of the complex formation processes in a Cu2+—L-glutamine system was obtained.

Thermodynamic characteristics of the acid-base equilibria of taurine in aqueous solutions, according to calorimetry data

Enthalpies of the neutralization and protonation of taurine (HL) are measured by direct calorimetry at 298.15 K and ionic strengths of 0.3, 0.5, and 1.0 (KNO3). The standard thermodynamic characteristics of HL protolytic equilibria are calculated.