Effect of pH on copper (II) chelate with l-histidine according to ESR spectra data
✍ Scribed by V.A. Abramenko; S.N. Bolotin; I.A. Nikolaienko
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 191 KB
- Volume
- 91
- Category
- Article
- ISSN
- 0167-7322
No coin nor oath required. For personal study only.
✦ Synopsis
Chelation of copper (II) with L-hi&line at different metal/ligand ratio and pH is investigated by means of ESR-spectroscopy.
Structural characteristics of 1:l and 1:2 composition chelates are determined by means of the spin matrix method, also the pH effect On the chelate structure is deduced.
Copper chelates with amino acids are of great interest as models of metal compounds with proteins, playing a principal part in human vital activity. The interest is backed up by the present information on copper (II) compounds with a-aminoacids as biologically active substance stabilizing different organism functions.
The goal of the work is to investigate the structure of copper (II) with L-histidine compositions. A number of contradictory data exist in literature on the pH effect on the character of the metallic ion bonding with a ligand. IR-spectrometric data [ 11 show that at lower pH CU (Il) ion bonds with the carboxyl oxygen. At higher pH a heptary chelate ring is proven to form, where the second donor atom is the nitrogen of the imidazole ring. Analysis of the chelate crystal structure, which crystallizes at pH 3.7, has shown that histidine molecules coordinate via the amino nitrogen and carboxy oxygen, both atoms are in the imidazole group protonated and do not participate in chelation,
We have investigated the effect of pH upon structural characteristics of chelates, determined by ESR-spectroscopy.