Complexation Of Dioxovanadium Research Articles

Complexation of Dioxovanadium (V) with CDTA in the Water + Methanol Solvent System

The solvent effect has been studied in this research for the interaction of the $$ {\text{VO}}_{2}^{ + } $$ cation with trans-1,2-diaminocyclohexane-N, N, N′, N′- tetraacetic acid monohydrate at T = 298 K, I = 0.10 mol·dm−3 sodium perchlorate, and in the range of 0–45 % water + methanol mixtures. UV absorbance data as a function of pH and dissociation constants, obtained from potentiometric titrations, were used for the determination of stability constants. The Kamlet–Abboud–Taft (KAT) model has been investigated for a plausible interpretation and calculation of the linear solvation energy relationship coefficient contribution to the formation of three species VO2H2L, VO2HL− and VO2L2−, which were identified in this work.

Complexation of Dioxovanadium(V) with D-(-)-Quinic Acid at Different Ionic Strengths Using Different Models Based on the Debye-Hückel Theory

The complex formation reaction between the dioxovanadium(V) cation \(\mathrm{VO}_{2}^{+}\) and D-(-)-quinic acid {(1R,3R,4S,5R)-(-)-1,3,4,5-tetrahydroxycyclohexane-1-carboxylic acid} has been studied in aqueous solutions. The UV data and the values of the derived conditional stability constants are presented and discussed in the light of one stoichiometric model for the reaction at T=298 K and different ionic strengths (0.10 to 1.00) mol⋅dm−3 of sodium chloride. Speciation diagrams and dissociation constants were obtained on the basis of UV spectroscopic measurements and potentiometric titrations, respectively. Our results show that one complex species, VO2L, exists in solution in the pH range of about 1.00 to 3.00. The parabolic, Specific Ion Interaction Theory (SIT), and extended Debye-Huckel type (EDH) models successfully describe the ionic strength dependence of the stability constants. A comparison with literature data is also reported.

Complexation of dioxovanadium(V) and dioxouranium(VI) by p-sulphonato-calix[4]arene in aqueous solution

The complexive ability of p-sulphonato-calix[4]arene towards dioxovanadium(V) and dioxouranium(VI) has been evaluated in acidic aqueous solution (pH 2) using UV–Vis spectrophotometric technique. The results showed that the ligand is capable to complex with the oxo-cations by 1:1 cation to ligand ratios. Formation constants of both systems have been determined at different temperatures (25 to 45 °C). Considering the formation constant values, the binding selectivity of the ligand towards the oxo-cations at 25 °C is in the order VO 2 + > UO 2 2+. The thermodynamic parameters have evaluated and are interpreted in terms of the importance of the various interactions responsible for the complexation. A roughly linear relationship between Δ H o and TΔ S o has been observed for the studied systems and those were reported in the literature. Finally, the host and guest desolvation involved in the complexation processes are discussed.

Complexation of Dioxovanadium(V) with Methyliminodiacetic Acid in NaClO4 Aqueous Solutions at Different Ionic Strengths by Using an Extended Debye−Hückel Equation, Specific Ion Interaction Theory, and Parabolic Equations

This paper mainly deals with solution equilibria between dioxovanadium(V) and the ligand methyliminodiacetic acid (MIDA) at different ionic strengths ranging from (0.1 to 0.9) mol·dm−3 sodium perchlorate and a pH range of (1.00 to 2.50) at T = 298 K. VO2HL and VO2L− were the main species which were obtained on the basis of the best fit at different ionic strengths. The application of a extended Debye−Hückel-type equation (EDH), specific ion interaction theory (SIT), and the parabolic model have been demonstrated for the representation of the ionic strength dependence of the stability and dissociation constants. Finally, the ionic strength dependence parameters were calculated on the basis of the aforementioned models, and the results were interpreted.

Application of the Parabolic Model, Specific Ion Interaction, and Debye−Hückel Theories for the Complexation of Dioxovanadium(V) with Ethylenediamine-N,N′-diacetic Acid

Interaction between dioxovanadium(V) and ethylenediamine-N,N′-diacetic acid (EDDA) has been investigated by potentiometric and UV spectrophotometric measurements in an aqueous solution of pH = 1.00 to 2.50 at I = (0.1 to 0.9) mol·dm−3 (NaClO4) and 25 °C. Different speciation models were used to detect the species, but the model that best fits the experimental data takes into account the formation of two species, VO2H2L+ and VO2HL. Distribution diagrams for the main species at different ionic strengths have been calculated as a function of pH. The dependence on ionic strength of the stability and dissociation constants was studied by using the extended Debye−Hückel-type equation (EDH), specific ion interaction theory (SIT), and the parabolic model. All of these approaches gave comparable and satisfactory results. Literature data were also considered and compared.

Complexation of Dioxovanadium(V) with Cysteine in Different Ionic Media: Salt Effects and Formation Constant

Complexation of Dioxovanadium(V) with Cysteine in Different Ionic Media: Salt Effects and Formation Constant

Complexation of Dioxovanadium(V) with Phenylalanine And Isoleucine at Different Ionic Strengths and Temperatures Using Debye-Huckel and Specific Ion Interaction Thoeries

Complexation of Dioxovanadium(V) with Phenylalanine And Isoleucine at Different Ionic Strengths and Temperatures Using Debye-Huckel and Specific Ion Interaction Thoeries

Complexation of Dioxovanadium(V) with Nitrilotriacetic Acid at Different Ionic Strengths by Using Specific Ion Interaction and Debye−Hückel Theories

This research has been undertaken to show the application of specific ion interaction theory (SIT) for the complexation of dioxovanadium(V) with nitrilotriacetic acid (NTA) at different ionic strengths of (0.1 to 1.0) mol·dm−3 sodium perchlorate as supporting electrolyte and pH range of 1.00 to 2.50 at 25 °C. Two species, VO2HL− and VO2H2L, have been detected according to curve fitting, which enables us to calculate the values of stability constants. Ionic strength dependence semiempirical parameters for the dissociation and stability constants were derived on the basis of an extended Debye−Hückel-type equation. The SIT model successfully described the ionic strength dependencies of the stability constant values.

Dielectric constant dependence of formation constants: complexation of dioxovanadium(V) with cysteine

The complexation of dioxovanadium(V) with L-cysteine was investigated in mixed solvent systems of methanol + water and dioxane + water at 25°C and 0.1 mol dm−3 ionic media, using a combination of potentiometric and spectrophotometric techniques. Sodium perchlorate solution was used to maintain the ionic strength. The compositions of the formed complexes were determined, and it was shown that dioxovanadium(V), VO, forms two mononuclear species with the ligand. The stability constants of the complexes formed are given in the above mixed solvent media and interpreted. Linear relationships are observed when plotted log β versus 1/D, where β and D represent formation and dielectric constants, respectively. The results are discussed in terms of the effect on mole fraction of the solvent both for protonation and complexation of cysteine. An attempt has been made to ascertain the nature of the correction factor in determining the pH in the mixed solvent solutions and the effect of increasing organic solvent on log β is also considered.

Complexation of dioxovanadium(V) with glycylglycine in sodium perchlorate aqueous solution

The present study deals with the complexation of dioxovanadium(V) with glycylglycine by a combination of potentiometric and spectrophotometric techniques in aqueous solution at 25 °C and 0.1 mol dm − 3 ionic strength (NaClO 4). The stability constants of the complexes formed and their stoichiometries are given and interpreted. The logarithms of the cumulative stability constant β xyz of the complex: [(oxometal) x (H) y (glycylglycine) z ] are respectively, log β 111 = 4.01 ± 0.1, log β 112 = 7.03 ± 0.10 and log β 112(OH) = 5.85 ± 0.11.

Solvent Effects on Complexation of Dioxovanadium(V) with Penicillamine in Methanol−Water Mixtures

The formation constants of the species formed in the systems H+ + dioxovanadium(V) + penicillamine and H+ + penicillamine have been determined in aqueous solutions of methanol at 25 °C and constant ionic strength, using spectrophotometric and potentiometric techniques. It was shown that dioxovanadium(V) forms two mononuclear 1:1 and 1:2 complexes with penicillamine. The formation constants in various media were analyzed in terms of Kamlet and Taft's parameters. Single-parameter correlation of the formation constants, β121 and β142, versus α (hydrogen-bond donor acidity) and β (hydrogen-bond acceptor basicity) is poor in all solutions, except for π* (dipolarity/polarizability), but multiparameter correlation represents significant improvement with regard to the single-parameter models. Linear relationships are observed when log β121 and log β142 are plotted versus π*. Finally, the results are discussed in terms of the effect of the solvent on complexation.

Ionic Strength Dependence of Formation Constants: Complexation of Dioxovanadium(V) with Tyrosine

The dependence on ionic strength of protonation of l-tyrosine and its complexation with dioxovanadium(V) is reported in sodium perchlorate solution as a background salt. The measurements have been performed at (25 ± 0.1) °C and various ionic strengths in the range (0.1 to 1.0) mol dm-3, using a combination of potentiometric and spectrophotometric techniques. The overall analysis of the present and the previous data dealing with the determination of stability constants at different ionic strengths allowed us to obtain a general equation, by which a formation constant determined at a fixed ionic strength can be calculated, with a good approximation, at another ionic strength, in the range (0.1 ≤ ionic strength ≤ 1.0) mol dm-3 sodium perchlorate.

Ionic Strength Dependence of Formation Constants: Complexation of Dioxovanadium(V) with Isoleucine

The stability constant for complexation of VO2+ with isoleucine has been determined at different ionic strengths ranging from 0.2 to 0.8 mol dm-3 of sodium perchlorate as a background salt, in the pH range 1.3−10 with high ligand to metal ratios, by a combination of potentiometric and spectrophotometric methods at (25 ± 0.1) °C. Our studies have shown that isoleucine forms mononuclear 1:1 and 1:2 complexes with VO2+ ion. The protonation constants of isoleucine were also determined potentiometrically at different ionic strengths.