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

Abstract

AbstractNew 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)‐β‐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 UV‐Vis 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 13C NMR 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.