Ligand H4BATA forms highly stable complex with bismuth(iii) in 1–2 min at room temperature.

Reprocessing of spent nuclear fuel (SNF) is an important task in a frame of ecology and rational use of natural resources. Uranium, as the main component of SNF (>95%), can be recovered for further use as fresh nuclear fuel. To minimize an amount of solid radioactive waste generated during SNF reprocessing, new extractants are under investigation. Diamides of 1,10-phenanthroline-2,9-dicarboxylic acid are perspective tetradentate N-donor ligands that form strong complexes with f-elements, which are soluble in polar organic solvents. As an example of three ligands of this class, we conducted a comparative study and showed how the substituent in the amide functional group affects the extraction ability toward uranyl nitrate from nitric acid media. We have performed a careful study (NMR, FT-IR, XRD, RMC-EXAFS) of the structures of synthesized complexes of new ligands with uranyl nitrate and used quantum mechanical calculations to explain the discovered regularities through.

The complexation properties towards Bi 3 + of benzoazacrown ligands with five (H 3 BA3A) and six (H 4 BATA) heteroatoms and corresponding number of acetic arms have been investigated. Complexation constants were determined via potentiometric titration for BA3ABi complex (logβ = 26.2) and refined for BATABi complex (logβ = 31.7). According to NMR, X-ray and EXAFS results, chelation of cation by H 3 BA3A appears to be outside the macrocyclic cavity both in the solid state and in the aqueous solution. This out-cage location despite the high stability constant causes serum and in vivo instability of complex of smaller azacrown H 3 BA3A in contrast to H 4 BATA. Whereas the larger macrocycle and four pendant arms of H 4 BATA provide long-range coordination effectively shielding the cation thereby ensuring high inertness in vitro, low accumulation of the radionuclide in the organs, and fast clearance.

The fractionation of high-level radioactive waste from nuclear power plants simplifies the handling of its components, and facilitates the reduction of radiotoxic effects on the environment. The search and study...

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