N-D-Gluconylglycine, a pseudopeptide derivative of glucono-1,5-lactone and glycine, was prepared and the equilibrium constants of its protonation and copper(II) co-ordination and the structures of the copper complexes formed were studied in aqueous solution by potentiometry, spectrophotometry, CD, EPR and 13C NMR relaxation. The parent complexes formed in an acidic medium have low stabilities, characteristic of carboxylate co-ordination. In the range pH 5-9 the amide group and the 2-OH group of the ligand undergo deprotonation. In parallel with these processes, one ligand is replaced from the copper(II) co-ordination sphere. For the species MLH-2, 3O,1N co-ordination in the equatorial plane is proposed. The EPR measurements indicate that dimeric species are also formed. At pH > 9, further base-consuming processes start as an indication of the deprotonation of other alcoholic hydroxy groups of the sugar moiety or the formation of mixed hydroxo complexes.
|Number of pages||6|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - Dec 1 1992|
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