Potentiometric and spectrophotometric study of the co-ordination compounds formed between copper(II) and dipeptides containing tyrosine
- 1 January 1981
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 6,p. 1331-1335
- https://doi.org/10.1039/dt9810001331
Abstract
Co-ordination compounds formed between L-tyrosylglycine (H2L), L-tyrosyl-L-leucine, L-tyrosyl-D-leucine, glycyltyrosine, L-leucyl-L-tyrosine, and L-tyrosineamide and H+ and Cu2+ have been studied potentiometrically at 25 °C and I= 0.10 mol dm–3(K[NO3]). In addition to the expected complex compounds [Cu(HL)]+, [CuL], [Cu(H–1L)]–, [Cu(H–2L)]2–, and [Cu(HL2)]–, a binuclear complex, [{Cu(H–1L)}2]2–, was found to form in the pH region 8–10.5 with tyrosylglycine and tyrosyl-D/L-leucine (giving a green solution) but was absent when tyrosine was the terminal carboxyl of the dipeptide. Spectrophotometric titrations showed this dimer to involve copper(II)–phenolate oxygen bonding. A structure for the dimer is described which explains the absence of a comparable dimer with glycyl- and leucyl-tyrosine, and the stereoselectivity found with the tyrosyl-D/L-leucine diastereo-isomers.Keywords
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