The compounds of leucine with copper (II) cations in aqueous solutions
https://doi.org/10.20914/2310-1202-2017-4-175-180
Abstract
The structure of alpha-amino acids offers the possibility of the formation of a large number of forms coordination compounds with cations of metals All forms of amino acids can participate in complexation reactions with metal cations: protonated form with metal ions adducts by coordinating with unshared electron pairs of oxygen atoms of carboxyl groups, the stability constants of such complexes are small and they usually like solvate complexes; bipolar and deprotonated forms not only adducts, but also chelation. The study of equilibrium in the system of amino acid - metal cation are most often carried out potentiometric and spectrophotometric methods, allowing fast, with good reproducibility to determine the equilibrium concentration and composition of the solution without displacement of the chemical equilibrium. In the literature, a chelate compound of leucine with copper (II) cations, formed in an alkaline medium with stability constants of 7.89 and 6.45, has been studied in sufficient detail. This paper presents a study of the conditions of complex formation in neutral aqueous solutions in the system containing aliphatic amino acid L, D-leucine and copper cations (II). The difference in the wavelengths corresponding to the maximum optical density indicates a change in the composition of the aqueous solution and the presence of copper leucinate compounds. The existence of a complex compound between bipolar leucine ions and copper (II) cations in neutral aqueous solutions of the composition (СuLеu4)2+ was proved by the spectrophotometric method of isomolar series. For the determination of stability constants using the method of J. Bjerrum with the following assumptions: an amino acid was regarded as monobasic weak acid, the stability constant of complex compounds was calculated as the average of all functional groups of leucine. Defined in the work a measure of stability constants protonated compounds composition (СuLеu4)2+ is equal to 4.27.
About the Authors
L. P. Bondareva
Voronezh state university of engineering technologies
Cand. Sci. (Chem.), associate professor, physical and analytical chemistry department, Revolution Av., 19 Voronezh, 394036, Russia
Cand. Sci. (Chem.), associate professor, physical and analytical chemistry department, Revolution Av., 19 Voronezh, 394036, Russia
E. V. Rusina
Voronezh state university of engineering technologies
student, physical and analytical chemistry department, Revolution Av., 19 Voronezh, 394036, Russia
student, physical and analytical chemistry department, Revolution Av., 19 Voronezh, 394036, Russia
D. V. Ovsyannikova
Voronezh state university of engineering technologies
Cand. Sci. (Chem.), engineer-ecologist, physical and analytical chemistry department, Revolution Av., 19 Voronezh, 394036, Russia
Cand. Sci. (Chem.), engineer-ecologist, physical and analytical chemistry department, Revolution Av., 19 Voronezh, 394036, Russia
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Review
For citations:
Bondareva L.P., Rusina E.V., Ovsyannikova D.V. The compounds of leucine with copper (II) cations in aqueous solutions. Proceedings of the Voronezh State University of Engineering Technologies. 2017;79(4):175-180. (In Russ.) https://doi.org/10.20914/2310-1202-2017-4-175-180
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