Biocoordination reactions in copper(II) ions and l-glutamic acid systems including tetramines: 1,11-diamino-4,8-diazaundecane or 1,12-diamino-4,9-diazadodecane

Abstract Metal-free systems of glutamic acid ( Glu ) with 3,3,3- tet or spermine ( Spm ) and ternary systems of Cu(II) ions with Glu and 3,3,3- tet or Spm were studied using the potentiometric and spectral methods: Vis, NMR and EPR. The composition, stability and mode of interaction in the formed (Glu)H x (PA) and Cu(Glu)H x (PA) species were established. Biogenic spermine interacts with Glu in a different way to its homologue 3,3,3- tet . In ternary systems Cu(II)/Glu/Spm, metallation involves all available nitrogen atoms from Spm, while in the form Cu(Glu)(3,3,3-tet) the uncoordinated –NH 2 group species 3,3,3- tet can create a centre for potential interaction with other bioligands. In glassy state at 77 K EPR shows that only stable CuL 2 type complexes exist with an axial symmetry. The geometrical structure of the complexes is discussed in the light of the results of alteration in complex structure when dynamic equilibrium at room temperature is changed during freezing. In this paper we have also quantitatively calculated how the change in the concentration of Cu(II) affects the level of molecular complexes. It was found that the introduction of Cu(II) into the studied binary ligand/ligand systems results in changes in the concentration of the molecular complexes in aqueous solution.