Investigating the Coordination/Binding Events of Biologically Relevant Monosaccharides with New Mononuclear Iron(III) and Zinc(II) Complexes in Aqueous Solution

摘要

New water-soluble mononuclear iron(III) and zinc(II) complexes, (Me4N)4[Fe2OCl6][Fe(pbal)Cl3]2 (1), (Me4N)[Fe(pbal)(NO3)3] (2) and (Me4N)[Zn(pbal)Cl2] (3)(Hpbal=N-(2-pyridylmethyl)-b-alanine) have been synthesized and fully characterized. The interactions of the complexes with biologically relevant monosaccharides, such as D-glucose, D-xylose and D-mannose have been studied by UV-Vis, 13C NMR and ESI-MS techniques in alkaline aqueous solution. All the monosaccharides bind to metal complexes in 1:1 molar ratio. Binding-induced gradual increase in the absorption intensities of 1 and 2 has been observed in the UVVis spectra, with a significant blue shift of absorption maxima of the complexes upon increasing the concentration of monosaccharides. The binding ability and binding mode of these monosaccharides with 3 are identified by their characteristic coordination-induced shift (CIS) values for carbon atoms C1 and C2 in the 13CNMR spectra. The ESI-MS for the complexes under the same experimental conditions but in the presence of one mol equiv. of the applied monosaccharides indicate the formation of complex/monosaccharide-bound associations in solution.