NMR study of the kinetics of the proton-exchange reactions in aqueous solutions of copper(II)-amino acid parent complexes

I. Nagypál, E. Farkas, A. Gergely

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Abstract

The rate constants of the proton-exchange reactions in aqueous solutions of the complexes of the copper(II) ion with the amino acids glycine, α-alanine, α-aminobutyric acid, norvaline, β-alanine, serine, threonine, asparagine, glutamine, aspartic acid, glutamic acid, ornithine and lysine were determined at 28°C by an NMR method. From a comparison of the literature formation rate constants and the exchange-rate data obtained in this work it was concluded that for the copper(II)-serine complex the kinetic activity of the zwitterion is caused by the axial coordination of the alcoholic OH group. The data obtained for the β-alanine complex indicate that the rate-determining step in the complex-formation is ring-closure. Equilibrium and kinetic data show that the thermodynamic and kinetic stabilities of the complexes of ligands containing an alcoholic OH group, an amide group or a carboxyl group in the β-position are higher than those of the complexes of ligands not containing a third potential donor group. The stability increase is explained by axial coordination of the functional group in the β-position. A third functional group in the γ or δ-position does not modify the equilibrium and kinetic behaviour of the complexes.

Original languageEnglish
Pages (from-to)2145-2149
Number of pages5
JournalJournal of Inorganic and Nuclear Chemistry
Volume37
Issue number10
DOIs
Publication statusPublished - 1975

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amino acids
Protons
Amino acids
Copper
Ion exchange
Nuclear magnetic resonance
Alanine
aqueous solutions
Amino Acids
copper
nuclear magnetic resonance
Kinetics
protons
kinetics
alanine
Serine
Functional groups
Acids
Rate constants
Ligands

Cite this

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title = "NMR study of the kinetics of the proton-exchange reactions in aqueous solutions of copper(II)-amino acid parent complexes",
abstract = "The rate constants of the proton-exchange reactions in aqueous solutions of the complexes of the copper(II) ion with the amino acids glycine, α-alanine, α-aminobutyric acid, norvaline, β-alanine, serine, threonine, asparagine, glutamine, aspartic acid, glutamic acid, ornithine and lysine were determined at 28°C by an NMR method. From a comparison of the literature formation rate constants and the exchange-rate data obtained in this work it was concluded that for the copper(II)-serine complex the kinetic activity of the zwitterion is caused by the axial coordination of the alcoholic OH group. The data obtained for the β-alanine complex indicate that the rate-determining step in the complex-formation is ring-closure. Equilibrium and kinetic data show that the thermodynamic and kinetic stabilities of the complexes of ligands containing an alcoholic OH group, an amide group or a carboxyl group in the β-position are higher than those of the complexes of ligands not containing a third potential donor group. The stability increase is explained by axial coordination of the functional group in the β-position. A third functional group in the γ or δ-position does not modify the equilibrium and kinetic behaviour of the complexes.",
author = "I. Nagyp{\'a}l and E. Farkas and A. Gergely",
year = "1975",
doi = "10.1016/0022-1902(75)80848-7",
language = "English",
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pages = "2145--2149",
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T1 - NMR study of the kinetics of the proton-exchange reactions in aqueous solutions of copper(II)-amino acid parent complexes

AU - Nagypál, I.

AU - Farkas, E.

AU - Gergely, A.

PY - 1975

Y1 - 1975

N2 - The rate constants of the proton-exchange reactions in aqueous solutions of the complexes of the copper(II) ion with the amino acids glycine, α-alanine, α-aminobutyric acid, norvaline, β-alanine, serine, threonine, asparagine, glutamine, aspartic acid, glutamic acid, ornithine and lysine were determined at 28°C by an NMR method. From a comparison of the literature formation rate constants and the exchange-rate data obtained in this work it was concluded that for the copper(II)-serine complex the kinetic activity of the zwitterion is caused by the axial coordination of the alcoholic OH group. The data obtained for the β-alanine complex indicate that the rate-determining step in the complex-formation is ring-closure. Equilibrium and kinetic data show that the thermodynamic and kinetic stabilities of the complexes of ligands containing an alcoholic OH group, an amide group or a carboxyl group in the β-position are higher than those of the complexes of ligands not containing a third potential donor group. The stability increase is explained by axial coordination of the functional group in the β-position. A third functional group in the γ or δ-position does not modify the equilibrium and kinetic behaviour of the complexes.

AB - The rate constants of the proton-exchange reactions in aqueous solutions of the complexes of the copper(II) ion with the amino acids glycine, α-alanine, α-aminobutyric acid, norvaline, β-alanine, serine, threonine, asparagine, glutamine, aspartic acid, glutamic acid, ornithine and lysine were determined at 28°C by an NMR method. From a comparison of the literature formation rate constants and the exchange-rate data obtained in this work it was concluded that for the copper(II)-serine complex the kinetic activity of the zwitterion is caused by the axial coordination of the alcoholic OH group. The data obtained for the β-alanine complex indicate that the rate-determining step in the complex-formation is ring-closure. Equilibrium and kinetic data show that the thermodynamic and kinetic stabilities of the complexes of ligands containing an alcoholic OH group, an amide group or a carboxyl group in the β-position are higher than those of the complexes of ligands not containing a third potential donor group. The stability increase is explained by axial coordination of the functional group in the β-position. A third functional group in the γ or δ-position does not modify the equilibrium and kinetic behaviour of the complexes.

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U2 - 10.1016/0022-1902(75)80848-7

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