Quenching mechanism of uranyl(VI) by chloride and bromide in aqueous and non-aqueous solutions
- A major hindrance in utilizing uranyl(VI) luminescence as a standard analytical tool, for example, in environmental monitoring or nuclear industries, is quenching by other ions such as halide ions, which are present in many relevant matrices of uranyl(VI) speciation. Here, we demonstrate through a combination of time-resolved laser-induced fluorescence spectroscopy, transient absorption spectroscopy, and quantum chemistry that coordinating solvent molecules play a crucial role in U(VI) halide luminescence quenching. We show that our previously suggested quenching mechanism based on an internal redox reaction of the 1:2-uranyl-halide-complex holds also true for bromide-induced quenching of uranyl(VI). By adopting specific organic solvents, we were able to suppress the separation of the oxidized halide ligand X-2(center dot-) and the formed uranyl(V) into fully solvated ions, thereby "reigniting" U(VI) luminescence. Time-dependent density functional theory calculations show that quenching occurs through the outer-sphere complex of U(VI)A major hindrance in utilizing uranyl(VI) luminescence as a standard analytical tool, for example, in environmental monitoring or nuclear industries, is quenching by other ions such as halide ions, which are present in many relevant matrices of uranyl(VI) speciation. Here, we demonstrate through a combination of time-resolved laser-induced fluorescence spectroscopy, transient absorption spectroscopy, and quantum chemistry that coordinating solvent molecules play a crucial role in U(VI) halide luminescence quenching. We show that our previously suggested quenching mechanism based on an internal redox reaction of the 1:2-uranyl-halide-complex holds also true for bromide-induced quenching of uranyl(VI). By adopting specific organic solvents, we were able to suppress the separation of the oxidized halide ligand X-2(center dot-) and the formed uranyl(V) into fully solvated ions, thereby "reigniting" U(VI) luminescence. Time-dependent density functional theory calculations show that quenching occurs through the outer-sphere complex of U(VI) and halide in water, while the ligand-to-metal charge transfer is strongly reduced in acetonitrile.…
Author details: | Toni HaubitzORCiDGND, Björn DrobotORCiDGND, Satoru TsushimaORCiD, Robin SteudtnerORCiD, Thorsten StumpfORCiDGND, Michael Uwe KumkeORCiDGND |
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DOI: | https://doi.org/10.1021/acs.jpca.1c02487 |
ISSN: | 1089-5639 |
ISSN: | 1520-5215 |
Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/33983019 |
Title of parent work (English): | The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory |
Publisher: | American Chemical Society |
Place of publishing: | Washington |
Publication type: | Article |
Language: | English |
Date of first publication: | 2021/05/13 |
Publication year: | 2021 |
Release date: | 2024/05/23 |
Volume: | 125 |
Issue: | 20 |
Number of pages: | 10 |
First page: | 4380 |
Last Page: | 4389 |
Funding institution: | Federal Ministry for Economic Affairs and Energy [02E11415F, 02E11860] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie |
DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften | |
Peer review: | Referiert |