Stability Constants Of Ternary Complexes Research Articles

Potentiometric determination of stability constants of ternary complexes of first row transition metal ions with ditopic azelaic acid dihydrazide and aspartic acid in aqueous medium

A Chemical speciation study of ternary complexes containing transition metal ions (Mn2+,Co2+,Ni2+, Cu2+ and Zn2+) with a ditopic novel ligand L ​= ​Azelaic acid dihydrazide (AZDH) and X ​= ​l-Aspartic acid of type [MmLlX xHh], (where m ​= ​1, 2; l ​= ​1; x ​= ​1, 2 and h ​= ​−2 to 5) in different ratios of M:L:X ​= ​1:1:1, 1:2:1, 2:1:1and 2:1:2 was carried out using pH -potentiometric method of data acquisition and applied to chemometric modelling methods of analysis. MINIQUAD-75 program was used for the resolution of the plausible species and their corresponding formation constants at 303 ​± ​0.1 ​K, and 0.01 ​M ionic strength. Species concentration distribution diagrams were generated using HySS program. Best-fit chemical models were selected on the basis of statistical parameters like Standard deviation (SD), U (sum of the squares of the residuals in mass balance equations), and chi-square test etc. Relatively stable ternary complexes were evaluated quantitatively using Δlog K formulation. All the formation constants for the species were compared for Irving-Williams order of stability.

Potentiometric studies on bioactive material species of ternary complexes in SLS-Water mixtures

Chemical speciation plays key role in understanding the physiological and biological aspects of metal ions and ligands in human body. The complexation of essential metal ions with Glycylglycine (GG) and Histamine (Him) in Sodium Lauryl Sulphate (SLS) has been presented in this study. The complexes formed in the present study are M L X H 2 , M L 2 X H 2 and M L X 2 H 3 . The Skewness values in the present study are from 0.05 to 0.84 for Ca(II), 0.03 to 0.93 for Mg(II) and 0.45 to 1.34 for Zn(II) and the χ2 values obtained the present study are ranging from 7.8250.37 for Ca(II), 6.1837.45 for Mg (II) and15.69143.67 for Zn(II). A very low standard deviation in log β values indicates the precision of the parameters. The advanced principles of mathematics and fuzzy logic have been employed to correlate chemical problems, which is called chemo metrics. In the present investigation potentiometer is used for analysis and the results obtained in the study have been processed through Gran plot method, SCPHD is used for best fit chemical model and MINIQUAD75 is used for refinement of results. An experiment has been conducted to understand the distribution of species, effect of surfactant on stability constants of ternary complexes, effect of influential parameters like concentration of alkali, acid, ligands and metal ions on the stability constants.

Potentiometric Studies on Bioactive Material Species of Ternary Complexes

Complexation of essential metal ions with glycylglycine and histamine in cetyltrimethylammonium bromide (CTAB) has been presented in this study, which targets insight in the distribution of species, effect of surfactants on stability constants of ternary complexes, and effect of concentration of alkali, acids, ligands, and metal ions on the stability constants. The studied complexes are MLXH2, ML2XH2, and MLX2H3. The advanced principles of mathematics and fuzzy logic have been employed to correlate chemical problems, known as chemo metrics. A potentiometer has been used for analysis, and the results obtained have been processed through gran plot method, SCPHD used for best fit chemical model. MINIQUAD75 has been used for refinement of the results.

Characterization by Potentiometric Procedures of the Stability Constants of the Binary and Ternary Complexes of Cu(II) and Duloxetine Drug with Amino Acids

Potentiometric titration method has been used to define stoichiometries and stability constants of ternary complexes of Cu(II) with duloxetine (D) and some selected amino acids (L). The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Cu(II) with the ligands were calculated from the potentiometric data using the HYPERQUAD program. The formation constants of the complexes formed in aqueous solutions and their concentration distributions as a function of pH were evaluated at 25°C and ionic strength 0.10 mol·L−1NaNO3. Respective stabilities of ternary complexes have been determined compared with the corresponding binary complexes in terms ofΔlog Kand %R.S. values. A novel binary and ternary duloxetine (D) drug with glycine and its Cu(II) complexes has been synthesized and characterized by several spectroscopic methods. Electronic spectra and magnetic susceptibility measurements reveal square planar geometry for both complexes. The elemental analyses and mass spectral data have justified the [Cu(D)(Gly)] and [Cu(D)Cl(H2O)] composition of complexes, where D = duloxetine and Gly = glycine. The EPR spectra of Cu(II) complexes support the mononuclear structures. Thermal properties and decomposition kinetics of Cu(II) complexes are investigated.

Computer Augmented Modeling of Complexes of L-Phenylalanine and Maleic Acid under Organic Media: Biomimetic Studies

Chemical speciation of ternary complexes of Co (II), Ni (II) and Cu (II) ions with L-Phenylalanine and Maleic acid has been studied by Calvin-Wilson technique at different concentration range of 0 - 50% v/v Organic-water mixture maintaining an ionic strength of 0.16 mol·L-1 at 298.0 K. Alkali metric titrations were carried out in different relative concentrations (M:L:X = 1:2.5:2.5, 1:2.5:5.0, 1:5.0:2.5) of metal (M) to phenylalanine (L) to maleic acid (X). The different values of stability constants of ternary complexes were calculated, and various models were refined with MINIQUAD75. The best fit chemical models containing MLXH, MLX and ML2X for Co (II), Ni (II) and Cu (II) species were arrived based on stability statistical parameters. The chemical speciation is discussed based on distribution diagrams, drawn using HYSS HYPERQUAD. Effect of errors in concentration of ingredients on stability constants was also studied.

Fluorescent ternary complexes of some biogenic amines and their metabolites with europium and oxytetracycline for applications in the chemical analysis

New ternary complexes of europium with oxytetracycline possessing the intense fluorescence have been obtained for prospective applications in the high-sensitive detection of biogenic amines and their metabolites in biological fluids. Their stability constants have been determined using the Foster–Hammick–Wardley method based on the fluorescent spectroscopy data. The dependence between structure differences, stability constants of ternary complexes of europium–oxytetracycline with biogenic amines, and their metabolites, and sensitivity of their determination has been established.

Speciation of ternary complexes of Ca(II), Zn(II) and Mn(II) with L-proline and L-valine in acetonitrile–water mixtures

Chemical speciation of ternary complexes of Ca(II), Zn(II) and Mn(II) with L-proline and L-valine was studied in various concentrations (0–60% v/v) of acetonitrile–water mixtures maintaining an ionic strength of 0.16 mol L-1 at 303.0 K. Alkalimetric titrations were carried out with different relative concentrations (M: L: X = 1:2.5:2.5, 1:2.5:5.0, 1:5.0:2.5) of metal (M) to L-proline (L) to L-valine (X). Stability constants of ternary complexes were calculated and various models were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The trend of the variation in the stability constants with changing dielectric constant (D) of the medium was explained based on the electrostatic interactions of the ligands, charge neutralisation, chelate effect, stacking interactions and hydrogen bonding. Distribution diagrams with pH at different compositions of aqua-organic mixtures and structures of plausible ternary complexes were also presented.

Influence of co-solvent on chemical speciation of ternary complexes of bi- and tri- dentate ligands with essential metalions

Chemical speciation of ternary complexes of Co(II), Ni(II), Cu(II) and Zn(II) ions with L-aspartic acid and ethylenediamine was studied pH-metrically in the concentration range of 0.0-60.0% v/v acetonitrile- and ethylene glycol-water mixtures maintaining an ionic strength of 0.16 mol L-1 at 303.0 K. Alkalimetric titrations were carried out in different relative concentrations (M:L:X = 1:2.5:2.5, 1:2.5:5.0, 1:5.0:2.5) of metal (M) to aspartic acid (L) to ethylenediamine (X). Stability constants of ternary complexes were calculated and various models were refined with MINIQUAD75. The best fit chemical models were selected based on statistical parameters and residual analysis. The species detected were MLX, ML2X, MLX2, MLX2H and MLX2H2 for Co(II), Ni(II), Cu(II) and Zn(II) in both media. The chemical speciation, metal bioavailability and transportation were explained based on the stability constants.

Synthesis, Characterization, and Physicochemical Studies of Mixed Ligand Complexes of Inner Transition Metals with Lansoprazole and Cytosine

Few complexes of inner transition metals [Th(IV), Ce(IV), Nd(III), Gd(III)] have been synthesized by reacting their metal salts with lansoprazole, 2-([3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methylsulfinyl)-1H-benzoimidazole and cytosine. All the complexes were synthesized in ethanolic medium. The yield percentage rangs from 80 to 90%. The complexes are coloured solids. The complexes were characterized through elemental analyses, conductance measurements, and spectroscopic methods (FT IR, FAB Mass,1H NMR and UV). An IR spectrum indicates that the ligand behaves as bidentate ligands. The metal complexes have been screened for their antifungal activity towardsAspergillus nigerfungi. The interaction of inner transition metals with lansoprazole, in presence of cytosine, has also been investigated potentiometrically at two different temperatures26±1°C and36±1°C and at 0.1 M (KNO3) ionic strength. The stability constants of ternary complexes indicate the stability order as Th(IV) < Ce(IV) < Gd(III) < Nd(III).logKvalues obtained are positive and suggest greater stabilization of ternary complexes. The values of thermodynamic parameters (free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) are also calculated.

Study of Ternary Complex Stability Constants of Some Toxic Metal Ions with l-Histidine and l-Glutamic Acid in Dioxan–Water Mixtures

The stability constants of ternary complexes of Pb(II), Cd(II) and Hg(II) ions with l-histidine and l-glutamic acid were determined pH metrically in the concentration range of 0–60 % v/v dioxan–water mixtures maintaining an ionic strength of 0.16 mol l−1 at 303.0 K. Alkalimetric titrations were carried out in different relative concentrations [M:L:X = 1.0:2.5:2.5, 1.0:2.5:5.0, 1.0:5.0:2.5 for Pb(II) and Cd(II) and 1.0:5.0:5.0, 1.0:5.0:10.0, 1.0:10.0:5.0 for Hg(II)] of metal (M) to histidine (L) to glutamic acid (X). Stability constants of ternary complexes were calculated and various models were refined with MINIQUAD75. The best fit chemical models were selected based on statistical parameters and residual analysis. The species detected are MLXH3, MLXH2, MLXH and ML2X for Pb(II), MLX2H2 and ML2X for Cd(II) and MLXH3 and MLXH2 for Hg(II). The relative stabilities of the mixed ligand complexes were compared with those of the binary complexes. The enhanced stability associated with the ternary complex is attributed to chelate effect, stacking interactions and hydrogen bonding.

Mixed ligand complexes of essential metal ions with L-glutamine and succinic acid in SLS-water mixtures

Speciation of mixed ligand complexes of Co(II), Ni(II) and Cu(II) with L-glutamine and succinic acid was studied in varying amounts (0.0-2.5% w/v) of sodium lauryl sulphate in aqueous solutions maintaining an ionic strength of 0.16 mol L-1 (NaCl) at 303.0 K. Titrations were carried out in the presence of different relative concentrations (M : L : X = 1 : 2 : 2, 1 : 4 : 2, 1 : 2 : 4) of metal (M) to L-glutamine (L) to succinic acid (X) with sodium hydroxide. Stability constants of ternary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The species detected were ML2X, MLX, MLXH and MLXH2 for Co(II), Ni(II) and Cu(II). Extra stability of ternary complexes compared to their binary complexes was believed to be due to electrostatic interactions of the side chains of ligands, charge neutralization, chelate effect, stacking interactions and hydrogen bonding. The species distribution with pH at different compositions of SLS and plausible equilibria for the formation of species were also presented.

Speciation studies of ternary complexes of some essential divalent metal ions with L-histidine and L-glutamic acid in DMSO-water mixtures

Chemical speciation of ternary complexes of Ca(II), Mg(II) and Zn(II) ions with L-histidine as the primary ligand (L) and L-glutamic acid as the secondary ligand (X) has been studied pH metrically in the concentration range of 0.0-60.0% v/v DMSO-water mixtures maintaining an ionic strength of 0.16 mol L-1 using sodium chloride at 303.0 K. Titrations were carried out in different relative concentrations (M:L:X = 1.0:2.5:2.5, 1.0:2.5:5.0, 1.0:5.0:2.5) of metal (M) to L-histidine to L-glutamic acid with sodium hydroxide. Stability constants of ternary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The predominant species detected for Ca(II), Mg(II) and Zn(II) are ML2XH2, MLXH2 and MLX2. Extra stability of ternary complexes compared to their binary complexes was explained to be due to electrostatic interactions of the side chains of ligands, charge neutralisation, chelate effect, stacking interactions and hydrogen bonding. The species distribution with pH at different compositions of DMSO and the plausible equilibria for the formation of species are discussed.

Investigations and chemical speciation of ternary complexes of bivalent metal ions with cephalexine as primary ligand and glycine and valine as secondary ligands

Studies on ternary complexes of bivalent metal ions viz. Cu, Pb II , Ni, Zn, Co, Cd, Mn, Mg and Ca, hereafter, M(II), with cephalexine (HCEX) as primary ligand and glycine (Gly) and valine (Val) as secondary ligands in 1:1:1 1 ratio, have been investigated by potentiometric technique at μ = 0.1 M (NaClO 4 ) and temp. = 25 ± 0.5° in aqueous medium. The stability constants and S min values of the ternary complexes M(II)-HCEX-Gly (A) and M(II)-HCEX-Val (B) have been calculated. The results have been discussed in terms of electrostatic and metal-ligand interaction. To visualize the nature of equilibrium and to evaluate the calculated stability constants of ternary complexes, species distribution diagrams have been plotted.

Mixed ligand complexes of toxic metal ions with L-glutamic acid and L-methionine in urea-water mixtures

Speciation of mixed ligand complexes of Pb(II), Cd(II) and Hg(II) with L-glutamic acid and L-methionine was studied in varying amounts (0.0-36.83%>w/v) of urea in aqueous solutions maintaining an ionic strength of 0.16 mol dm -3 (NaNO3) at 303 K. Titrations were carried out in the presence of different relative concentrations (M : L : X = 1 : 2: 2, 1 : 2 : 4, 1 : 4: 2) of metal (M) to L-glutamic acid (L) to L-methionine (X) with sodium hydroxide. Stability constants of ternary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The species detected were MLXH for Pb(II), MLX and ML2X for Cd(II), and MLX and MLXH2 for Hg(II). Extra stability of ternary complexes compared to their binary complexes was believed to be due to electrostatic interactions of the side chains of ligands, charge neutralization, chelate effect, stacking interactions and hydrogen bonding. The species distribution with pH at different compositions of urea and plausible equilibria for the formation of species were also presented. The bioavailability of the toxic metal ions is explained based on the speciation.

Study on guanidino–carboxylate interactions in copper(II) ternary complexes of guanidinoacetic acid with glutamic and aspartic acids

The possibility of occurrence of biological relevant guanidino–carboxylate interactions was investigated in ternary systems involving guanidinoacetic (Gaa) and glutamic acid (Glu), aspartic acid (Asp) or glycine (Gly). The study was done in solution using potentiometry, ultraviolet visible and EPR spectroscopy. The stability constants of the ternary complexes as well as the binary ones were potentiometrically determined ( T=25 °C, μ=0.1 mol l −1, KNO 3). The order of the stability constants of ternary complexes was CuAspGaa>CuGluGaa>CuGlyGaa. Δlog K(log β CuLGaa−(log β CuL+log β CuGaa) L=Glu, Asp or Gly) showed that Asp and Glu favored more stable ternary complexes while Gly formed a less stable ternary complex than its binary ones. Comparison between statistical and experimental log β CuLGaa suggested guanidino–carboxylate interactions in CuAspGaa and CuGluGaa, involving the guanidino group from Gaa and the non-coordinated-carboxylate group from Glu or Asp, possibly through hydrogen bonds.

Ternary complexes of catechol and amino acids

Stability constants of ternary complexes of Cu(II) containing catechol or analogues and amino acids, tryptophan, tyrosine, or phenylalanine have been determined potentiometrically at 25°C in aqueous medium having ionic strength of 0.2 M NaOH. scogs computer program was used. The stability order has been explained on the basis of hydrophobic interactions of the noncoordinated groups of the ligands. The complexes have been isolated in the solid state and characterized by elemental analysis, magnetic measurements, IR, and electronic spectral studies.

Polarographic Determination of Stability Constants of Ternary Complexes of Cadmium with α-Alanine as Primary Ligand and Oxalic Acid as Secondary Ligand

Polarographic Determination of Stability Constants of Ternary Complexes of Cadmium with α-Alanine as Primary Ligand and Oxalic Acid as Secondary Ligand

Determination of the stability constant of the ternary complex formed in the copper-bipyridyl-eriochrome cyanine R system, by an isosbestic point-spectrophotometric method

This paper reports a new method for determining the stability constants of ternary complexes, based on analysis of isosbestic points. First, it is necessary to determine the absolute molar absorptivities of the various species concerned, then their concentrations and the stability constant. In this method, the approximate treatment of classical photometric methods is not required. The conditional constant can be calculated directly from the measured data.

Ternary complexes in solution: Complex formation between copper(II), zinc(II), cadmium(II) and ligands of biological importance

The stability constants of ternary complexes of theMAL type have been determined for Cu(II), Zn(II) and Cd(II). The ligands chosen for this study belong to the biologically important ones viz. Bipyridyl (A) and Nitrilotriacetic acid (L). LogK MAL values for Cu(II), Zn(II) and Cd(II) are 11.42, 10.67 and 9.72, respectively, at temp.=25°C and μ=0.1M (KNO3); the order is discussed.

Mixed ligand chelates of Cd 2+ with thiosulphate as primary ligand and adipic, itaconic and phthalic acids as secondary ligands

The stability constants of ternary complexes of cadmium with thiosulphate (TS) as a primary ligand and adipic (ADPT), itaconic (ITA) and phthalic (PHLT) acids as secondary ligands have been determined at 25 ± 0.5°C and μ = 2.5 M (NaNO 3). Cadmium ion individually forms 1:1, 1:2 and 1:3 complexes with all the ligands. The ternary chelates are formed by simultaneous equilibria. The values for the mixed species β 11, β 12 and β 21 are are calculated for TS-ADPT, TS-ITA, TS-PHLT systems. The complexation constants of these species were also evaluated following the procedure suggested by Watters. The negative value of β 12 in the TS-PHLT system, indicates the absence of [Cd(TS)(PHLT) 2] 4−.