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Srivastava A, Ali SM, Dumpala RMR, Kumar S, Kumar P, Rawat N, Mohapatra PK. Unusual redox stability of pentavalent uranium with hetero-bifunctional phosphonocarboxylate: insight into aqueous speciation. Dalton Trans 2024; 53:7321-7339. [PMID: 38591248 DOI: 10.1039/d4dt00173g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
The +5 state is an unusual oxidation state of uranium due to its instability in the aqueous phase. As a result, gaining information about its aqueous speciation is extremely difficult. The present work is an attempt in that direction and it provides insight into the existence of a new pentavalent species in the presence of hetero-bifunctional phosphonocarboxylate (PC) chelators, other than the carbonate ion, in the aqueous medium. The aqueous chemistry of pentavalent uranium species with three environmentally relevant PCs was probed using electrochemical and DFT methods to understand the redox energy and kinetics of conversion of the U(VI)/U(V) couple, stability, structure, stoichiometry, binding modes, etc. Interestingly, pentavalent uranium complexes with PCs are quite persistent over a wide range of pH starting from acidic to alkaline conditions. The PC chelators block the cation-cation interaction (CCI) of U(V) through strong hetero-bidentate chelation and intermolecular hydrogen bonding (IMHB) interactions which stabilize the pentavalent metal ion against disproportionation. For uranyl species in the presence of PCs, acting as chelators, CV plots were obtained at varying pH values from 2 to 8. The obtained results indicate an irreversible single redox peak involving U(VI) to U(V) conversion and association of a coupled chemical reaction with the electron transfer step. ESI-MS studies were performed to understand the speciation effect on the U(VI)/U(V) redox couple with varying pH. Speciation modelling of U(V) with the PC ligands was carried out, which indicated that the U(V) is redox stable in nearly 47% of the pH region in the presence of the PCs as compared to the carboxylate-based chelators. The free energy and reduction potential of the U(V) complexes and the reduction free energy and disproportionation free energy for the U(VI)/U(V) couple were determined by DFT computations in the presence of the PCs. In situ spectroelectrochemical spectra were recorded to provide evidence for the existence of U(V) species with PCs in the aqueous medium and to acquire its absorption spectra. The present study is highly significant for understanding the coordination chemistry of pentavalent uranium species, accurate modelling of uranium, and isolation of U(V).
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Affiliation(s)
- Ashutosh Srivastava
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085.
| | - Sk Musharaf Ali
- Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai, India-400085
| | | | - Sumit Kumar
- Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085
| | - Pranaw Kumar
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085
| | - Neetika Rawat
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085.
| | - P K Mohapatra
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai, India-400085.
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Srivastava A, Dumpala RMR, Rawat N, Tomar B. Electrochemical, spectroscopic and theoretical studies on redox speciation of neptunium with phenylphosphonic acid. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2018.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Tatosian IJ, Iacovino AC, Van Stipdonk MJ. Collision-induced dissociation of [U VI O 2 (ClO 4 )] + revisited: Production of [U VI O 2 (Cl)] + and subsequent hydrolysis to create [U VI O 2 (OH)] . RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:1085-1091. [PMID: 29645301 DOI: 10.1002/rcm.8135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 03/23/2018] [Accepted: 03/26/2018] [Indexed: 06/08/2023]
Abstract
RATIONALE In a previous study [Rapid Commun Mass Spectrom. 2004;18:3028-3034], collision-induced dissociation (CID) of [UVI O2 (ClO4 )]+ appeared to be influenced by the high levels of background H2 O in a quadrupole ion trap. The CID of the same species was re-examined here with the goal of determining whether additional, previously obscured dissociation pathways would be revealed under conditions in which the level of background H2 O was lower. METHODS Water- and methanol-coordinated [UVI O2 (ClO4 )]+ precursor ions were generated by electrospray ionization. Multiple-stage tandem mass spectrometry (MSn ) for CID and ion-molecule reaction (IMR) studies was performed using a linear ion trap mass spectrometer. RESULTS Under conditions of low background H2 O, CID of [UVI O2 (ClO4 )]+ generates [UVI O2 (Cl)]+ , presumably by elimination of two O2 molecules. Using low isolation/reaction times, we found that [UVI O2 (Cl)]+ will undergo an IMR with H2 O to generate [UVI O2 (OH)]+ . CONCLUSIONS With lower levels of background H2 O, CID experiments reveal that the intrinsic dissociation pathway for [UVI O2 (ClO4 )]+ leads to [UVI O2 (Cl)]+ , apparently by loss of two O2 molecules. We propose that the results reported in the earlier CID study reflected a two-step process: initial formation of [UVI O2 (Cl)]+ by CID, followed by a very rapid hydrolysis reaction to leave [UVI O2 (OH)]+ .
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Affiliation(s)
- Irena J Tatosian
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
| | - Anna C Iacovino
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
| | - Michael J Van Stipdonk
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
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Van Stipdonk MJ, Iacovino A, Tatosian I. Influence of Background H 2O on the Collision-Induced Dissociation Products Generated from [UO 2NO 3]<sup/>. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:1416-1424. [PMID: 29654536 DOI: 10.1007/s13361-018-1947-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 03/18/2018] [Accepted: 03/18/2018] [Indexed: 06/08/2023]
Abstract
Developing a comprehensive understanding of the reactivity of uranium-containing species remains an important goal in areas ranging from the development of nuclear fuel processing methods to studies of the migration and fate of the element in the environment. Electrospray ionization (ESI) is an effective way to generate gas-phase complexes containing uranium for subsequent studies of intrinsic structure and reactivity. Recent experiments by our group have demonstrated that the relatively low levels of residual H2O in a 2-D, linear ion trap (LIT) make it possible to examine fragmentation pathways and reactions not observed in earlier studies conducted with 3-D ion traps (Van Stipdonk et al. J. Am. Soc. Mass Spectrom. 14, 1205-1214, 2003). In the present study, we revisited the dissociation of complexes composed of uranyl nitrate cation [UVIO2(NO3)]+ coordinated by alcohol ligands (methanol and ethanol) using the 2-D LIT. With relatively low levels of background H2O, collision-induced dissociation (CID) of [UVIO2(NO3)]+ primarily creates [UO2(O2)]+ by the ejection of NO. However, CID (using He as collision gas) of [UVIO2(NO3)]+ creates [UO2(H2O)]+ and UO2+ when the 2-D LIT is used with higher levels of background H2O. Based on the results presented here, we propose that product ion spectrum in the previous experiments was the result of a two-step process: initial formation of [UVIO2(O2)]+ followed by rapid exchange of O2 for H2O by ion-molecule reaction. Our experiments illustrate the impact of residual H2O in ion trap instruments on the product ions generated by CID and provide a more accurate description of the intrinsic dissociation pathway for [UVIO2(NO3)]+. Graphical Abstract ᅟ.
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Affiliation(s)
- Michael J Van Stipdonk
- Department of Chemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA.
| | - Anna Iacovino
- Department of Chemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
| | - Irena Tatosian
- Department of Chemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
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Kumar P, Jaison PG, Telmore VM, Sadhu B, Sundararajan M. Speciation of uranium-mandelic acid complexes using electrospray ionization mass spectrometry and density functional theory. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:561-571. [PMID: 28035726 DOI: 10.1002/rcm.7817] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 12/20/2016] [Accepted: 12/28/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Mandelic acid is a complexing agent employed for the liquid chromatographic separation of actinides. However, the types of species and the structural details of the uranyl-mandelate complexes are still unknown. Understanding the nature of these complex species would provide better insight into the mechanism of their separation in liquid chromatography. METHODS Formation of different species of the uranyl ion (UO2 ) with mandelic acid was studied using electrospray ionization mass spectrometry (ESI-MS) with a quadrupole time-of-flight analyzer. The different species of uranyl nitrate with mandelic acid (MA) at ligand (L) to metal ratios in the range 1-10 were examined in both positive and negative ion modes. The stability of different species with the possible pathways of formation was scrutinized using density functional theory (DFT) calculations. RESULTS In negative ion mode, nitrate-containing UO2 (MA)1 , UO2 (MA)2 and UO2 (MA)3 species were found in good abundance. In positive ion mode, under-coordinated uranyl-mandelate species, and solvated (S) species of types UO2 (MA)1 (S), UO2 (MA)1 (S)2 and UO2 (MA)2 (S), were observed whereas nitrate-containing species were absent. Interestingly, doubly and singly charged dimeric species were also identified in positive ion mode. The theoretically computed energetics of the various species are in close agreement with their experimentally observed intensities in ESI-MS. CONCLUSIONS The most intense peak observed in ESI-MS, UO2 (MA)3 , was found to be the energetically most favorable amongst different UO2 (MA)n type species. Metal-ligand equilibria studied in the two modes yielded similar results. The combined experimental and quantum chemical investigations predict that T-shape complexes may be formed even in the gas phase. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Pranaw Kumar
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - P G Jaison
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - V M Telmore
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - Biswajit Sadhu
- Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - Mahesh Sundararajan
- Theoretical Chemistry Section, Bhabha Atomic Research Centre, Mumbai, 400085, India
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Srivastava A, Kumar P, Tomar BS. Redox speciation of uranium with phenylphosphonic acid (PPA) in aqueous medium. RADIOCHIM ACTA 2016. [DOI: 10.1515/ract-2016-2652] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Studies on complexation of uranium with organophosphorous ligands in aquatic systems are important from point of view of mobility of uranium in environment. In the present paper, we report the results of complexation of U(VI) by a model ligand for organophosphorus functionalities in humic substances (HS), that is, phenylphosphonic acid (PPA), using electro analytical techniques. The UO2
2+ has been found to form 1:1 and 1:2 complexes with mono-protonated PPA (HPhPO3
−) and 1:1 complex with non-protonated PPA, (PhPO3)2−, with the latter complex (UO2PhPO3) dominating over the other two species. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to investigate the redox behavior of UO2PhPO3 species and to explore the kinetics of its reduction by evaluating heterogeneous electron-transfer kinetic (D, k
s and α) parameters. The diffusion coefficient (D) value was found to be 6.76×10−5 cm2 s−1 and 5.03×10−5 cm2 s−1 at pH 5 and 3, respectively, with rate constant, k
s=0.304×10−3 cm/s. Using the DeFord and Hume formalism the stability constant (log β) of UO2PhPO3 was calculated to be (6.98±0.12), which is in agreement with the literature data. Electrospray ionization mass spectrometry (ESI-MS) studies corroborated the existence of UO2PhPO3 complex.
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Affiliation(s)
- Ashutosh Srivastava
- Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai-400085, India
| | - Pranaw Kumar
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai-400085, India
| | - Bhupendra S. Tomar
- Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai-400085, India
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A ω-mercaptoundecylphosphonic acid chemically modified gold electrode for uranium determination in waters in presence of organic matter. Talanta 2016; 151:119-125. [DOI: 10.1016/j.talanta.2016.01.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 11/24/2022]
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Lu G, Forbes TZ, Haes AJ. Evaluating Best Practices in Raman Spectral Analysis for Uranium Speciation and Relative Abundance in Aqueous Solutions. Anal Chem 2015; 88:773-80. [DOI: 10.1021/acs.analchem.5b03038] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Grace Lu
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Tori Z. Forbes
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Amanda J. Haes
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
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The structural and spectroscopic studies of complexes with diethyl benzylphosphonate and diethyl (carboxymethyl)phosphonate in solution and in the solid state. Polyhedron 2013. [DOI: 10.1016/j.poly.2013.06.045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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