Study of local structure of Cu-II complex of 2-amino-1,6-anhydro-2-deoxy-beta-D-glucopyranose in aqueous solution by X-ray absorption spectroscopy

The interaction between 2-amino-1,6-anhydro-2-deoxy-beta-D-glucopy (I) and the Cu-II ion in aqueous solution at pH = 5.5 was studied by Cu K-XANES and EXAFS measurements. Analysis of the EXAFS spectra showed that the complex is hexacoordinated, with Cu-O / N-eq and Cu-O-ax distances of 193 and 220 p m, respectively. The EXAFS Fourier transform clearly revealed a peak ascrib ed to nonbonded Cu...C (r = 275 pm) and Cu...Cu (r = 299 pm) interactions, indicating the formation of dimeric species and of chelate rings of the sug ar ligands around the Cu-II ion. The most likely structure of the complex i s suggested.