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Title: Selectivity in ligand binding to uranyl compounds: A synthetic, structural, thermodynamic and computational study

The uranyl cation (UO₂²⁺) is the most abundant form of uranium on the planet. It is estimated that 4.5 billion tons of uranium in this form exist in sea water. The ability to bind and extract the uranyl cation from aqueous solution while separating it from other elements would provide a limitless source of nuclear fuel. A large body of research concerns the selective recognition and extraction of uranyl. A stable molecule, the cation has a linear O=U=O geometry. The short U-O bonds (1.78 Å) arise from the combination of uranium 5f/6d and oxygen 2p orbitals. Due to the oxygen moieties being multiply bonded, these sites were not thought to be basic enough for Lewis acidic coordination to be a viable approach to sequestration. The goal of this research is thus to broaden the coordination chemistry of the uranyl ion by studying new ligand systems via synthetic, structural, thermodynamic and computational methods. It is anticipated that this fundamental science will find use beyond actinide separation technologies in areas such as nuclear waste remediation and nuclear materials. The focus of this study is to synthesize uranyl complexes incorporating amidinate and guanidinate ligands. Both synthetic and computational methods are used to investigatemore » novel equatorial ligand coordination and how this affects the basicity of the oxo ligands. Such an understanding will later apply to designing ligands incorporating functionalities that can bind uranyl both equatorially and axially for highly selective sequestration. Efficient and durable chromatography supports for lanthanide separation will be generated by (1) identifying robust peptoid-based ligands capable of binding different lanthanides with variable affinities, and (2) developing practical synthetic methods for the attachment of these ligands to Dowex ion exchange resins.« less
Authors:
 [1]
  1. Univ. of California, Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
1183657
Report Number(s):
DOE/NEUP--11-3049
11-3049; TRN: US1600276
DOE Contract Number:
AC07-05ID14517
Resource Type:
Technical Report
Research Org:
Univ. of California, Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE). Nuclear Energy University Programs (NEUP)
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; CATIONS; URANYL COMPOUNDS; AQUEOUS SOLUTIONS; NUCLEAR FUELS; SEAWATER; EXTRACTION; CHEMICAL BONDS; LIGANDS; URANYL COMPLEXES; LEWIS ACIDS; RARE EARTH COMPLEXES; AMIDINES; GUANIDINES; CHEMICAL PREPARATION; RARE EARTHS