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Exploring crown-ether functionalization on the stabilization of hexavalent neptunium
Mikaela M Pyrch1, James M Williams1, Tori Z Forbes1
1Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA. tori-forbes@uiowa.edu.
Chemical Communications (Cambridge, England)
|July 18, 2019
Summary
Functionalizing crown ethers with dicyclohexano-18-crown-6 (DCH-18C6) enhances the stability of neptunium(VI) oxidation states, preventing reduction and improving resistance to radiolysis in radiochemical separations.
Area of Science:
- Radiochemistry
- Inorganic Chemistry
- Materials Science
Background:
- Crown ethers like 18-crown-6 (18C6) are vital for selective metal cation separation in radiochemistry.
- Previous studies showed 18C6 interacting with neptunium (Np), forming Np(V) complexes and causing Np(VI) reduction.
Purpose of the Study:
- To investigate the effect of crown ether functionalization on neptunium speciation and stability.
- To explore the interactions between neptunium(V) and neptunium(VI) with dicyclohexano-18-crown-6 (DCH-18C6).
Main Methods:
- Synthesis and single crystal X-ray diffraction of two neptunium(VI) compounds with DCH-18C6.
- Raman spectroscopy to characterize the synthesized compounds.
- Solution studies involving Np(VI), Np(V), and mixed Np(V)/Np(VI) systems in the presence of DCH-18C6.
Main Results:
- Two novel compounds, [K(DCH-18C6)]2[NpO2Cl4] and [Na(DCH-18C6)]2[NpO2Cl4], were successfully crystallized and characterized.
- Neptunium exhibited redox stability in solution with functionalized crown ethers.
- Preferential crystallization of Np(VI) DCH-18C6 solids was observed.
Conclusions:
- Functionalization of crown ethers, specifically with DCH-18C6, enhances redox stability of neptunium.
- The DCH-18C6 system demonstrates increased resistance to radiolysis compared to non-functionalized ethers.
- This suggests that functionalized crown ethers can improve the stability of Np(VI) oxidation states in radiochemical applications.
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