STABILITY CONSTANTS OF L-ASPARAGINE AND L-LEUCINE COMPLEXES  WITH SOME LANTHANIDE IN AQUEOUS SOLUTIONS AT 298.15 K

Lanthanides have a high affinity toward ligands containing donor oxygen atoms, especially amino acids and complexons. The study of the processes of complexation of amino acids with f-element cations provides valuable information for solving problems of supramolecular chemistry, molecular recognition and chiral sensitivity of biological substrates. As a rule, f-elements are not components of biopolymers, but they are spectral label probes, which are important in the bioinorganic chemistry of metals. Quantitative estimation of the stability of complexes is necessary, first of all, to search for an internal connection between the constants themselves and then to find correlations between the stability of complexes and the properties of the complexing agent, the ligand, and the system as a whole. Such correlation dependencies make it possible to calculate a priori, or at least estimate the stability constants of new complexes, and also to better understand the influence of the nature of the chemical bond and the properties of the system as a whole on the formation and stability of complex compounds. In the present work, the complexation of neodymium, lanthanum with L-asparaginat ion and samarium, cerium with L-leucinat ion at 298.15 K and ionic strength values of 0.5 mol/l was studied by potentiometric titration and the stability constants of the complexes formed were determined. The values of the stability constants found allow us to perform rigorous thermodynamic calculations of the equilibria of these amino acids in salt solutions. The data obtained, in particular, can be used to reliably interpret the results of calorimetric studies of the complexation of lanthanides with the participation of the studied amino acids.Forcitation:Lytkin A.I., Chernyavskaya N.V., Smirnova D.K. Stability constants of L-asparagine and L-leucine complexes with some lanthanide in aqueous solutions at 298.15 K. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 37-41

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Equilibrium of aliphatic amino acids on ion exchangers forming complexes in the presence of copper (II) and nickel (II) cations

Proceedings of the Voronezh State University of Engineering Technologies ◽

10.20914/2310-1202-2019-3-217-224 ◽

2019 ◽

Vol 81 (3) ◽

pp. 217-224

Author(s):

L. P. Bondareva ◽

Y. S. Peregudov ◽

A. V. Astapov

Keyword(s):

Amino Acids ◽

Stability Constant ◽

Stability Constants ◽

Distribution Coefficients ◽

Complex Compounds ◽

Exchange Chromatography ◽

Ion Exchanger ◽

Ion Exchangers ◽

Aliphatic Carboxylic Acid ◽

The Stability

The task of isolating and separating amino acids from aqueous solutions exists in various industries. The traditional method of isolation is ligand exchange chromatography. When choosing a cation for ligand-binding chromatography based on its binding strength with the ion exchanger, often used as a sulfonated polystyrene ion exchanger keeps the copper (II) firmly enough, and therefore, it is easily replaced by other cations. Chelating ion exchangers charge cations of copper (II), which hold these ions firmly enough. In this case, separating a mixture of substances, it is due to differences in the constants of complexation agents and complexes distribution coefficients. The study of the interaction of amino acids with the aliphatic carboxylic acid, the exchange of phosphoric acid cations and the amino carboxylic and amino phosphonic polyampholytes has shown a significant effect of the pH of the medium on the nature of the sorption equilibria. Under certain conditions, in the phase of the ion exchanger in the form of complexing metal cations, the formation of new sorption centers is possible, which occur upon sorption of amino acids in the formation of mixed ligand compounds: the sorbent complex may simultaneously comprise amino acids and attached functional groups of the sorbent as ligands. The influence of the hydrogen index of the medium primarily affects the change in the nature of the formed complex compounds in the sorbent phase and the equilibrium solution and the ratio of their stability constants. If the stability constant of the ion exchanger complex is higher than the stability constant of the compound with a low molecular weight ligand, then the sorbed copper cations interact with incoming methionine ions without breaking the metal – functional group of the ion exchanger coordination bond. If the ratio of stability constants is the opposite, then the predominant elution of copper (II) cations occurs with the formation of complex compounds with an amino acid in an aqueous solution.

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Synthesis of Metal Oxide Nanoparticles of Nickel(II), Vanadium(V) and Potentiometric Determination of the Stability Constants of Their Complexes with Histidine and Glutamine at Different Temperatures in Aqueous Solutions

Asian Journal of Chemistry ◽

10.14233/ajchem.2013.13002 ◽

2013 ◽

Vol 25 (3) ◽

Keyword(s):

Metal Oxide ◽

Aqueous Solutions ◽

Stability Constants ◽

Metal Oxide Nanoparticles ◽

Potentiometric Determination ◽

Oxide Nanoparticles ◽

Different Temperatures ◽

The Stability

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A comparative study of the determination of the stability constants of inclusion complexes of p-sulfonatocalix[4]arene with amino acids by RP-HPLC and 1H NMR

Journal of the Chemical Society Perkin Transactions 2 ◽

10.1039/b005497f ◽

2001 ◽

pp. 258-263 ◽

Cited By ~ 67

Author(s):

Olga I. Kalchenko ◽

Florent Perret ◽

Nicole Morel-Desrosiers ◽

Anthony W. Coleman

Keyword(s):

Amino Acids ◽

Comparative Study ◽

Inclusion Complexes ◽

Stability Constants ◽

1H Nmr ◽

Rp Hplc ◽

The Stability

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The affinity of aldehydic compounds to complex formation. Nickel(II) and cobalt(II) complexes with 2-pyridinecarboxaldehyde

Canadian Journal of Chemistry ◽

10.1139/v77-362 ◽

1977 ◽

Vol 55 (14) ◽

pp. 2613-2619 ◽

Cited By ~ 3

Author(s):

M. S. El-Ezaby ◽

M. A. El-Dessouky ◽

N. M. Shuaib

Keyword(s):

Complex Formation ◽

Aqueous Solutions ◽

Stability Constants ◽

Metal Ion ◽

Experimental Conditions ◽

Complex Species ◽

Spectrophotometric Methods ◽

Complex Equilibria ◽

The Stability ◽

Hydroxy Groups

The interactions of Ni(II) and Co(II) with 2-pyridinecarboxaldehyde have been investigated in aqueous solutions at μ = 0.10 M (KNO3) at 30 °C. The stability constants of different complex equilibria have been determined using potentiometric methods. Spectrophotometric methods were also used in the case of the nickel(II) – 2-pyridinecarboxaldehyde system. It was concluded that nickel(II) and cobalt(II), analogous to copper(II), enhance hyrdation of 2-pyridinecarboxaldehyde prior to deprotonation of one of the geminal hydroxy groups. Complex species of 1:1 as well as 1:2 metal ion to ligand composition exist under the experimental conditions used.

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