Europium(III) Meets Etidronic Acid (HEDP): A Coordination Study Combining Spectroscopic, Spectrometric, and Quantum Chemical Methods
Etidronic acid (1-Hydroxyethylidene-1,1-diphosphonic acid, HEDP, H<sub>4</sub>L) is a proposed decorporation agent for U(VI). This paper studied its complex formation with Eu(III), an inactive analog of trivalent actinides, over a wide pH range, at varying metal-to-ligand ratios (M:L) an...
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MDPI AG
2023-05-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/28/11/4469 |
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| author | Anne Heller Christian Senwitz Harald Foerstendorf Satoru Tsushima Linus Holtmann Björn Drobot Jerome Kretzschmar |
| author_facet | Anne Heller Christian Senwitz Harald Foerstendorf Satoru Tsushima Linus Holtmann Björn Drobot Jerome Kretzschmar |
| author_sort | Anne Heller |
| collection | DOAJ |
| description | Etidronic acid (1-Hydroxyethylidene-1,1-diphosphonic acid, HEDP, H<sub>4</sub>L) is a proposed decorporation agent for U(VI). This paper studied its complex formation with Eu(III), an inactive analog of trivalent actinides, over a wide pH range, at varying metal-to-ligand ratios (M:L) and total concentrations. Combining spectroscopic, spectrometric, and quantum chemical methods, five distinct Eu(III)−HEDP complexes were found, four of which were characterized. The readily soluble EuH<sub>2</sub>L<sup>+</sup> and Eu(H<sub>2</sub>L)<sub>2</sub><sup>−</sup> species with log β values of 23.7 ± 0.1 and 45.1 ± 0.9 are formed at acidic pH. At near-neutral pH, EuHL<sup>0</sup><sub>s</sub> forms with a log β of ~23.6 and, additionally, a most probably polynuclear complex. The readily dissolved EuL<sup>−</sup> species with a log β of ~11.2 is formed at alkaline pH. A six-membered chelate ring is the key motif in all solution structures. The equilibrium between the Eu(III)–HEDP species is influenced by several parameters, i.e., pH, M:L, total Eu(III) and HEDP concentrations, and time. Overall, the present work sheds light on the very complex speciation in the HEDP–Eu(III) system and indicates that, for risk assessment of potential decorporation scenarios, side reactions of HEDP with trivalent actinides and lanthanides should also be taken into account. |
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| language | English |
| last_indexed | 2024-03-11T03:01:50Z |
| publishDate | 2023-05-01 |
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| series | Molecules |
| spelling | doaj.art-960dff282a8c4938bf0ec6c12fb1e62d2023-11-18T08:17:03ZengMDPI AGMolecules1420-30492023-05-012811446910.3390/molecules28114469Europium(III) Meets Etidronic Acid (HEDP): A Coordination Study Combining Spectroscopic, Spectrometric, and Quantum Chemical MethodsAnne Heller0Christian Senwitz1Harald Foerstendorf2Satoru Tsushima3Linus Holtmann4Björn Drobot5Jerome Kretzschmar6Chair of Radiochemistry/Radioecology, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, GermanyChair of Radiochemistry/Radioecology, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, GermanyInstitute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, GermanyInstitute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, GermanyInstitute of Radioecology and Radiation Protection, Leibniz Universität Hannover, 30419 Hannover, GermanyInstitute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, GermanyInstitute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, GermanyEtidronic acid (1-Hydroxyethylidene-1,1-diphosphonic acid, HEDP, H<sub>4</sub>L) is a proposed decorporation agent for U(VI). This paper studied its complex formation with Eu(III), an inactive analog of trivalent actinides, over a wide pH range, at varying metal-to-ligand ratios (M:L) and total concentrations. Combining spectroscopic, spectrometric, and quantum chemical methods, five distinct Eu(III)−HEDP complexes were found, four of which were characterized. The readily soluble EuH<sub>2</sub>L<sup>+</sup> and Eu(H<sub>2</sub>L)<sub>2</sub><sup>−</sup> species with log β values of 23.7 ± 0.1 and 45.1 ± 0.9 are formed at acidic pH. At near-neutral pH, EuHL<sup>0</sup><sub>s</sub> forms with a log β of ~23.6 and, additionally, a most probably polynuclear complex. The readily dissolved EuL<sup>−</sup> species with a log β of ~11.2 is formed at alkaline pH. A six-membered chelate ring is the key motif in all solution structures. The equilibrium between the Eu(III)–HEDP species is influenced by several parameters, i.e., pH, M:L, total Eu(III) and HEDP concentrations, and time. Overall, the present work sheds light on the very complex speciation in the HEDP–Eu(III) system and indicates that, for risk assessment of potential decorporation scenarios, side reactions of HEDP with trivalent actinides and lanthanides should also be taken into account.https://www.mdpi.com/1420-3049/28/11/4469lanthanidesTRLFSNMRATR-FT-IRDFTESI-MS |
| spellingShingle | Anne Heller Christian Senwitz Harald Foerstendorf Satoru Tsushima Linus Holtmann Björn Drobot Jerome Kretzschmar Europium(III) Meets Etidronic Acid (HEDP): A Coordination Study Combining Spectroscopic, Spectrometric, and Quantum Chemical Methods Molecules lanthanides TRLFS NMR ATR-FT-IR DFT ESI-MS |
| title | Europium(III) Meets Etidronic Acid (HEDP): A Coordination Study Combining Spectroscopic, Spectrometric, and Quantum Chemical Methods |
| title_full | Europium(III) Meets Etidronic Acid (HEDP): A Coordination Study Combining Spectroscopic, Spectrometric, and Quantum Chemical Methods |
| title_fullStr | Europium(III) Meets Etidronic Acid (HEDP): A Coordination Study Combining Spectroscopic, Spectrometric, and Quantum Chemical Methods |
| title_full_unstemmed | Europium(III) Meets Etidronic Acid (HEDP): A Coordination Study Combining Spectroscopic, Spectrometric, and Quantum Chemical Methods |
| title_short | Europium(III) Meets Etidronic Acid (HEDP): A Coordination Study Combining Spectroscopic, Spectrometric, and Quantum Chemical Methods |
| title_sort | europium iii meets etidronic acid hedp a coordination study combining spectroscopic spectrometric and quantum chemical methods |
| topic | lanthanides TRLFS NMR ATR-FT-IR DFT ESI-MS |
| url | https://www.mdpi.com/1420-3049/28/11/4469 |
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