Reactions of mental chelates. I. The reactions of copper (II) chelates of some beta-diketones and their related compounds with glycine, diglycine and triglycine.
The reactions of copper(II) chelates of β-diketones such as acetylacetone, benzoylacetone, dibenzoylmethane and benzoylacetaldehyde and of chelates of their related compounds such as salicylaldehyde and 2-hydroxyacetophenone with glycine or glycylglycine were investigated. Only bis(salicylaldehydato)copper(II) and bis(benzoylacetaldehydato)copper(II) reacted with glycine to form the respective glycinato-Schiff base complexes, whereas the other chelates did not react with glycine under the same condition. On the other hand, all the chelates except bis(dibenzoylmethanato)copper(II) reacted with glycylglycine to form the respective glycylglycinato-Schiff base complexes. The reaction at pH 4.5 between bis(salicylaldehydato)copper(II) and triglycine resulted in the hydrolytic cleavage of peptide bond, producing the salicylideneglycylglycinatocuprate(II) and free glycine. As the results of this investigation, five new copper(II) chelates were synthesized and characterized.
The Stability of Fused Rings in Metal Chelates. IX. Copper(II) and Nickel(II) Complexes of Schiff Bases Derived from Salicylaldehyde and Dipeptides Containing Glycine and/or β-Alanine
Copper(II) and nickel(II) complexes of Schiff bases derived from salicylaldehyde(Sal) and dipeptides containing glycine and/or β-alanine have been prepared. It has been found that Schiff base ligands containing glycylglycine (Gly·Gly), glycyl-β-alanine (Gly·β-Ala) or β-alanylglycine (β-Ala·Gly) as the peptide moieties give rise to square-planar, quadridentate copper(II)- and nickel(II)-chelates, while the N-salicylidene-β-alanyl-β-alanine (Sal=β-Ala·β-Ala) does not form the same type of copper(II)- or nickel(II)-chelate. It is concluded on the basis of spectrophotometric, polarographic and other measurements that the stability decreases in the order 6-5-5-([Cu(Sal=Gly·Gly)])≥6-5-6-([Cu(Sal=Gly·β-Ala)])≥6-6-5-([Cu(Sal=β-Ala·Gly)])>>6-6-6-([Cu(Sal=β-Ala·β-Ala)])fused-ring system.
Metal chelate compounds of glycylglycine and glycylglycylglycine.
Abstract The preparation of copper(II), cobalt(III), and nickel(II) chelates of glyclyglycine and of glycylglycylglycine is described and the structures of the compounds are deduced with the aid of analytical data and titration curves. For both ligands it was found that association with these metal ions was accompanied by the displacement of a hydrogen ion from each peptide linkage.