Fundamental Study on Uranyl Coordination With Biological Ligands Analyzed by Herfd-xanes Spectroscopy

ABSRACT Uranium has the potential to form complexes with biological ligands in body fluids upon internal exposure. The coordination of U with biological ligands was analyzed by using high energy resolution fluorescence detected X-ray absorption near edge fine structure (HERFD-XANES) at U L ₃ edge. A spectra of uranyl compounds such as uranium dioxide, uranyl acetate, carbonate, phosphate, hydroxide, and cysteine were measured by HERFD-XANES spectroscopy. Symmetry of the compounds was discussed on the results of linear combination least-squares fit modeling of the spectra. Pre-edge peak of U(VI) samples in HERFD-XANES spectra were different from those obtained with conventional XANES spectra. It was suggested that uranyl carbonate has the highest symmetry of the uranyl compounds studied. Differences between the shoulder peak of carbonate and that of acetate in the HERFD-XANES were observed, and peak energies in the experimental data were supported by those in the calculated data based on the finite difference method for near-edge structure. This finding suggests that HERFD-XANES can successfully distinguish coordination structure with similar ligands in contrast to conventional XANES.