Effects of mixed-ligand complex formation on deprotonation of amide groups in acid amides and peptides

I. Sóvágó, Bela Harman, Arthur Gergely, Barbara Radomska

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Abstract

The stability constants of the parent complexes of the A ligands glycinamide, glycylglycinamide, and N-acetylhistidine with copper(II), and of the mixed complexes formed with the B ligands glycine, 2,3-diaminopropionic acid, tiron, histamine, L-histidine, and 2,2′-bipyridyl, have been determined from pH-metric measurements. It has been found that glycinamide forms mixed-ligand complexes of composition [CuAB] and [CuABH-1] (charges omitted), and most favourably with histamine, L-histidine, or 2,2′-bipyridyl. In the glycylglycinamide complexes of type [CuABH-1] the B ligand is co-ordinated to a considerable extent via two equatorial sites, while the bonding in the complex [CuABH-2], similarly to the other dipeptides, is mainly axial-equatorial. In the parent complexes of copper(II) with N-acetylhistidine and with N-acetylhistamine, deprotonation and co-ordination of the amide group could not be detected. It has been found, however, that the presence of B ligands containing an aromatic N donor permits deprotonation of the amide groups in both N-acetylhistidine and N-acetylhistamine.

Original languageEnglish
Pages (from-to)235-239
Number of pages5
JournalJournal of the Chemical Society, Dalton Transactions
Issue number2
DOIs
Publication statusPublished - 1986

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Deprotonation
Amides
Ligands
Peptides
Acids
2,2'-Dipyridyl
Histidine
Histamine
Copper
1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt
Dipeptides
Glycine
Chemical analysis
N-acetylhistidine

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Effects of mixed-ligand complex formation on deprotonation of amide groups in acid amides and peptides. / Sóvágó, I.; Harman, Bela; Gergely, Arthur; Radomska, Barbara.

In: Journal of the Chemical Society, Dalton Transactions, No. 2, 1986, p. 235-239.

Research output: Contribution to journalArticle

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