Mixed ligand complexes of nickel(II) with imidazoles and some dipeptides

Abstract

The computer based analysis of the <i>p</i>H titration data in the Ni(II)-imidazole (him)/histamine (hist)/L-histidine(his) (A)glycyl-L-phenylalanine(glyphe), glycyl-L-tyrosine(glytyr) and

L-tyrosylglycine (tyrgly) (B) systems shows the presence of NiAB, NiABH_-1, NiA₂B or NiAB₂ mixed ligand species. The results demonstrate that him, hist and his(A) are respectively mono-, bi- and tri-dentate and the dipeptide(B) ligands are bidentate in NiAB, NiA₂B and NiAB₂ complexes. The amide deprotonated dipeptide (BH_-1) appears to bind in a tridentate mode in the NiABH_-1 species in the him(A) systems, while the trends in results clearly demonstrate the bidentate binding of (BH_-1) in the hist/his(A) mixed ligand systems.

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