Structure of Cu(II) complexes of D-ribose and D-glucosamine. Electronic, ESR and EXAFS studies.

Interactions between D-ribose or D-glucosamine and Cu(II) ion have been stu died by electronic spectra, ESR, and Cu K-XANES and -EXAFS measurements. Al l data have shown that (1:1) Cu(II)-sugar complexes are formed in aqueous s olution at high pH. The have ESR spectra of the two Cu(II)-sugar complexes indicated the presence of a dimeric species via hydroxide oxygen atoms in t he solution. From the analysis of the EXAFS spectra the oxygen coordination geometry around Cu(II) ion and the Cu(II)-O bond lengths within the Cu(II) -sugar complexes are not very different from those of the hexaaqua Cu(II) i on. EXAFS Fourier transforms have clearly shown a peak ascribed to non-bond ed Cu(II)...C interactions, indicating the formation of chelate rings of th e sugar-ligand around the Cu(II) ion. The most likely structure of the Cu(I I)-sugar complexes is proposed.