COMPARATIVE XANES STUDIES OF SOME COPPER(II) MIXED-LIGAND AMINO-ACID COMPLEXES IN SOLID AND AQUEOUS-SOLUTION FORMS

The spectra of the five copper(II) mixed ligand amino acid complexes h ave been recorded in solid as well as in aqueous solution forms. The p rimary ligand used in four of the complexes is threonine (Thr), while in the fifth complex it is glycylglycine (GlyGly). The secondary ligan ds used are: histidene (Hist), glycylglycine (GlyGly), alpha amino but yric acid (Abu) and valine (Val) in the first four complexes whereas v aline (Val) remains secondary ligand in the fifth sample. The chemical shift values are larger in solid state as compared to the correspondi ng values in aqueous form, indicating more ionic nature of the complex es in solid state. Further by evaluating the changes in the shift valu es in going from solid to solution state in the complexes, the relativ e effect of dissolution in water has been estimated.