Aqueous curium(III) phosphate species characterized by time-resolved laser-induced fluorescence spectroscopy

Moll, Henry; Brendler, Vinzenz; Bernhard, Gert

doi:10.1524/ract.2011.1878

Cited by 16 publications

(32 citation statements)

References 22 publications

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“…The successful application of this software was demonstrated by earlier work on the complexation of curium(III), europium(III), and americium(III) with various ligands. 31,33,36,43 Input parameters for the data fitting were the total concentrations of the heavy metals and citrate, the stability constants of the heavy metal hydroxides, 44 the protonation constants of the ligand species, 11,12 the pH, and the measured sample spectra. For all constants, the values valid for I = 0.1 M have been used and, where necessary, recalculated from I = 0 M using the Davies equation.…”

Section: Discussionmentioning

confidence: 99%

“…The luminescence spectrum of the Cm 3+ aqua ion is characterized by a single emission band at 593.5 ± 0.2 nm representing the 6 D 7/2 → 8 S 7/2 transition and a luminescence lifetime of 67 ± 1 μs equalling 9 water molecules in the first hydration sphere. 8,33,39,69 Spectroscopic alterations that indicate the complexation of the Cm 3+ ion were observed at each pH. In general, the emission band is shifted to longer wavelengths.…”

Section: Trlfs Spectra Of Curium(iii) Citrate Complexesmentioning

confidence: 95%

“…This results from the formation of the dominant curium(III) species at high pH, which is the poorly water soluble Cm(OH) 3 . 33 At ≥7.5 × 10 −4 M citrate, luminescence is detectable again but steady-state and especially time-resolved spectra are very noisy. However, the emission maximum is even more red-shifted to 607.5 ± 0.1 nm than at pH 8.1 and the luminescence lifetime is about 155 ± 20 μs corresponding to 3.3 ± 0.5 water molecules.…”

Section: Trlfs Spectra Of Curium(iii) Citrate Complexesmentioning

confidence: 99%

“…This technique is highly suitable to determine the binding form of a luminescent metal ion at trace concentrations. 8,[31][32][33][34] From both single and time-resolved experiments, valuable parameters, such as emission wavelengths and luminescence lifetimes, are obtained. These parameters are sensitive to the chemical environment of the heavy metal ions and vary in dependence on the ligand.…”

Section: Introductionmentioning

confidence: 99%

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Curium(iii) citrate speciation in biological systems: a europium(iii) assisted spectroscopic and quantum chemical study

et al. 2012

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Citrate complexes are the dominant binding form of trivalent actinides and lanthanides in human urine at pH < 6. Hence, an accurate prediction of the speciation of these elements in the presence of citrate is crucial for the understanding of their impact on the metabolism of the human organism and the corresponding health risks. We studied the complexation of Cm(III) and Eu(III), as representatives of trivalent actinides and lanthanides, respectively, in aqueous citrate solution over a wide pH range using time-resolved laser-induced fluorescence spectroscopy. Four distinct citrate complexes were identified and their stability constants were determined, which are MHCit(0), M(HCitH)HCit(2-), M(HCit)(2)(3-), and M(Cit)(2)(5-) (M = Cm, Eu). Additionally, there were also indications for the formation of MCit(-) complexes. Structural details on the EuHCit(0) and EuCit(-) complexes were obtained with FT-IR spectroscopy in combination with density functional theory calculations. IR spectroscopic evidence for the deprotonation of the hydroxyl group of the citrate ion in the EuCit(-) complex is presented, which also revealed that the complexation of the Eu(3+) ion takes place not only through the carboxylate groups, like in EuHCit(0), but additionally via the hydroxylate group. In both EuHCit(0) and EuCit(-) the carboxylate binding mode is mono-dentate. Under a very low metal : citrate ratio that is typical for human body fluids, the Cm(III) and Eu(III) speciation was found to be strongly pH-dependent. The Cm(III) and Eu(III) citrate complexes dominant in human urine at pH < 6 were identified to be Cm(HCitH)HCit(2-) and a mixture of Eu(HCitH)HCit(2-) and EuHCit(0). The results specify our previous in vitro study using natural human urine samples (Heller et al., Chem. Res. Toxicol., 2011, 24, 193-203).

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Section: Discussionmentioning

confidence: 99%

Section: Trlfs Spectra Of Curium(iii) Citrate Complexesmentioning

confidence: 95%

Section: Trlfs Spectra Of Curium(iii) Citrate Complexesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Curium(iii) citrate speciation in biological systems: a europium(iii) assisted spectroscopic and quantum chemical study

et al. 2012

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“… a TRLFS: time-resolved laser-induced fluorescence spectroscopy. b Recalculated using the values published by Jordan et al and the log 10 β 0 and Δ R H m 0 values for the reaction H + + H 2 PO 4 – ⇌ H 3 PO 4 at each temperature from Grenthe et al c R.T. : room temperature. d From the value recalculated by Moll et al for the equilibrium Cm 3+ + 2H + + PO 4 3– ⇌ Cm(H 2 PO 4 ) 2+ . e N.A. : not available. f As mentioned by Silva et al, the reaction involves exchange between ligands and solvation water molecules and the equilibrium constant was corrected for changes in water activity. …”

Section: Introductionmentioning

confidence: 99%

Revisiting the Complexation of Cm(III) with Aqueous Phosphates: What Can We Learn from the Complex Structures Using Luminescence Spectroscopy and Ab Initio Simulations?

et al. 2021

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The coordination chemistry of Cm(III) with aqueous phosphates was investigated by means of laser-induced luminescence spectroscopy and ab initio simulations. For the first time, in addition to the presence of Cm(H 2 PO 4 ) 2+ , the formation of Cm(H 2 PO 4 ) 2 + was unambiguously established from the luminescence spectroscopic data collected at various H + concentrations (−log 10 [H + ] = 2.52, 3.44, and 3.65), ionic strengths (0.5−3.0 mol•L −1 NaClO 4 ), and temperatures (25−90 °C). Complexation constants for both species were derived and extrapolated to standard conditions using the specific ion interaction theory. The molal enthalpy Δ R H m 0 and molal entropy Δ R S m 0 of both complexation reactions were derived using the integrated van't Hoff equation and indicated an endothermic and entropy-driven complexation. For the Cm(H 2 PO 4 ) 2 + complex, a more satisfactory description could be obtained when including the molal heat capacity term. While monodentate binding of the H 2 PO 4 − ligand(s) to the central curium ion was found to be the most stable configuration for both complexes in our ab initio simulations and luminescence lifetime analyses, a different temperaturedependent coordination to hydration water molecules could be deduced from the electronic structure of the Cm(III)−phosphate complexes. More precisely, where the Cm(H 2 PO 4 ) 2+ complex could be shown to retain an overall coordination number of 9 over the entire investigated temperature range, a coordination change from 9 to 8 was established for the Cm(H 2 PO 4 ) 2 + species with increasing temperature.

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Actinides: Biogeochemistry

Boukhalfa

Neu

2018

Encyclopedia of Inorganic and Bioinorganic Chemistry

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Transuranic elements are highly reactive and form multiple oxidation states and complex species that can co‐exist, which underlies their fascinating inorganic, bioinorganic, and environmental chemistry. Because they are ubiquitous, microorganisms through their natural processes can interact with transuranic elements to change their speciation through both direct microbe‐transuranics interactions and indirect change of physical and chemical conditions in their environment. Understanding how microbial processes affect transuranic elements broadens our knowledge of fundamental transuranic chemistry, increases our understanding of the impact of biological and environmental receptors and metals on each other, and enables the development of applications in separation, remediation technologies, mammalian decorporation strategies, and nuclear repository design. Microorganisms and biogeochemical processes transform metals via numerous and varied chemical, biological, and geological processes, many of which have yet to be characterized in detail even for main group elements. The focus of this article is a brief overview of transuranic species that form in the environment and the biogeochemical processes that transform them. The primary processes that have been well studied for transuranic species are as follows: (i) complexation with inorganic/bioinorganic ligands within, and produced by, bacteria; (ii) complexation by organic ligands, including microbial metabolites, and transuranic bio‐associations; and (iii) biomineralization to form transuranic materials and mineral analogs.

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Aqueous curium(III) phosphate species characterized by time-resolved laser-induced fluorescence spectroscopy

Cited by 16 publications

References 22 publications

Curium(iii) citrate speciation in biological systems: a europium(iii) assisted spectroscopic and quantum chemical study

Curium(iii) citrate speciation in biological systems: a europium(iii) assisted spectroscopic and quantum chemical study

Revisiting the Complexation of Cm(III) with Aqueous Phosphates: What Can We Learn from the Complex Structures Using Luminescence Spectroscopy and Ab Initio Simulations?

Actinides: Biogeochemistry

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