D. F. Pyreu

Thermodynamics of mixed-ligand complexation of mercury(II) ethylenediaminetetraacetate with histidine and lysine in aqueous solution

The formation of mixed-ligand complexes HgEdtaIm2−, HgEdtaL3−, HgEdtaHL2−, and (HgEdta)2L5− (L is histidine, lysine; Im is imidazole) was studied by calorimetry, pH-metry, and NMR spectroscopy. The thermodynamic parameters (logK, ΔrG0, ΔrH, ΔrS) for the reactions of complex formation at 298.15 K and ion strength of 0.5 (KNO3) were determined. The most likely coordination mode for the complexone and amino acid in the mixed complexes was identified.

Enthalpies and constants of dissociation for D,L-Alanyl-D,L-Serine at 298 K

Protolytic equilibria in aqueous solutions of D,L-alanyl-D,L-serine are studied by means of potentiometry and calorimetry. The dissociation constants and thermal effects of this reaction of the dipeptide are determined at 298.15 K and ionic strengths of 0.1, 0.3, 0.5, and 1.0 (KNO3). The standard thermodynamic characteristics (pK°, ΔrG°, ΔrH°, and ΔrS°) of the studied equilibria are calculated. The final results are compared with the corresponding data on the related compounds.

The thermal effects of acid-base interactions in aqueous solutions of D,L-α-alanyl-glycine

The heat effects of protolytic equilibria of D,L-α-alanyl-glycine at 298.15 K and ionic strengths of 0.1, 0.3, 0.5, and 1.0 (KNO3) were determined by direct calorimetry. The standard thermodynamic characteristics of these equilibria were calculated. The results were compared with the data on related compounds.

Mixed-ligand complexation of iron(III) ethylenediaminetetraacetate with iminodiacetate and ethylenediamine in aqueous solution

The formation of the heteroleptic complexes FeEdtaIda3− and FeEdtaEn−(Ida2− is the iminodiacetate anion and En is ethylenediamine) was examined by direct calorimetry, pH potentiometry, and spectrophotometry at 298.15 K and the ionic strength I = 0.5 (KNO3). A possible way of coordination of the ligands in the heteroleptic complexes was discussed.

The heats of interaction of L-glutamine and L-glutamic acid with KOH and HNO3 in aqueous solutions

The heat effects of protolytic equilibria of L-glutamine and L-glutamic acid at 298.15 K and ionic strengths of 0.1, 0.3, 0.5, and 1.0 (KNO3) were determined by the direct calorimetric method. Standard thermodynamic characteristics of the equilibria were calculated.

Thermochemical study of the complex formation of copper(II) and nickel(II) iminodiacetates with amino acids in aqueous solutions

The formation of mixed-ligand complexes in the M(II)–Ida–L systems (M = Cu, Ni, L = His, Orn, Lys), where Ida is the iminodiacetic acid residue, was studied by pH-metry, calorimetry, and spectrophotometry. The thermodynamic parameters (logK, ΔrG0, ΔrH, ΔrS) of formation of the complexes were determined at 298.15 K and the ionic strength I = 0.5 (KNO3). The most probable mode of coordination of the chelating agent and the amino acid in the mixed-ligand complexes was elucidated.

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.

Mixed Complex Formation of Lead(II) and Mercury(II) Ethylenediaminetetraacetates with Thiourea in an Aqueous Solution

The formation of mixed-ligand complexes HgEdtaThio2−, HgEdtaS2O34−, PbEdtaThio2−, and Pb(Thio)i2+, i = 1, 2; Thio is thiourea) was studied by calorimetry, pH metry, and 1H and 13C NMR spectroscopy. The thermodynamic parameters (logK, ΔrG0, ΔrH, and ΔrS) for the formation of the complexes at 298.15 K and the ionic strength I = 0.5(NaClO4) were determined. The most probable coordination mode of the ligands in the mixed complex was considered.

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.