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Uranium / Sugar phosphate / Complex formation / Potentiometric titration / TRLFS / EXAFSSummary. The complex formation in the aqueous systems of uranium(VI) with glucose 6-phosphate (G6P) and fructose 6-phosphate (F6P) were studied using potentiometric titration, TRLFS, and EXAFS. Two complexes with a uranyl-to-ligand ratio of 1 : 1 and 1 : 2 for both sugars were observed. Complex stability constants were determined by potentiometric titration for both complexes to be log β 11 (G6P) = 5.89 ± 0.40, log β 12 (G6P) = 9.45 ± 0.08, log β 11 (F6P) = 5.72 ± 0.21, and log β 12 (F6P) = 9.54 ± 0.09. Stability constants could be determined with TRLFS under the specific experimental conditions only for the 1 : 1 complexes: log β 11 (G6P) = 6.35 ± 0.28, and log β 11 (F6P) = 5.66 ± 0.17.The TRLFS measurements results show the UO 2 G6P complex to exhibit no fluorescence properties. For this system, only a decrease of the fluorescence intensity with increasing ligand concentration was observed. For the UO 2 F6P system, a red shift of the fluorescence emission bands of about 8 to 9 nm compared to the free uranyl ion was observed. The fluorescence emission wavelengths of the UO 2 F6P complex were determined to be 483, 496, 518, 542, and 567 nm, and the lifetime of this complex is 0.13 ± 0.05 µs.Uranium L III -edge EXAFS measurements at pH 3.5, 4.0, and 5.5 yielded a shortened U−O eq bond distance (2.30 ± 0.02 to 2.37 ± 0.02 Å), compared to the UO 2 2+ (H 2 O) 5 ion (2.40 ± 0.02 Å), due to a monodentate coordination via the oxygen atoms of the phosphate group.

SummaryThe complex formation of uranium(VI) with

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