Deactivation processes of the lowest excited state of [UO2(H2O)5]2+ in aqueous solution

Formosinho, Sebastião J.; Burrows, Hugh D.; Miguel, Maria G.; Azenha, M. Emília; Saraiva, Isabel M.; Ribeiro, A. Catarina D. N; Khudyakov, I. V.; Gasanov, R. G.; Bolte, Michèle; Sarakha, Mohamed

doi:10.1039/b300346a

Cited by 52 publications

(36 citation statements)

References 86 publications

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“…The doubly-charged UO 2 2ϩ observed at m/z 135 in the presence of D 2 O can result from DO · radical addition followed by DO Ϫ anion elimination as suggested earlier [39]. The absence of doubly-charged UO 2 2ϩ in the spectrum resulting from reaction with CD 3 OD indicates that a similar process does not occur with the methoxy radical.…”

Section: Ion-molecule Reactions In the Gas-phase With D 2 O And Cd 3 supporting

confidence: 53%

“…Other ions in Figure 3 The appearance of deuterium in these ions is interesting, since it has been proposed previously that hydrated UO 2 2ϩ in solution abstracts a hydrogen atom from water during photolysis, ultimately forming UO 2 ϩ and H ϩ along with an OH radical [39]. A similar solution reaction has been proposed with CH 3 OH [39].…”

Section: Ion-molecule Reactions In the Gas-phase With D 2 O And Cd 3 mentioning

confidence: 60%

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Ions generated from uranyl nitrate solutions by electrospray ionization (ESI) and detected with fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometry

Pasilis

Somogyi

Herrmann

et al. 2006

J. Am. Soc. Mass Spectrom.

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Electrospray ionization (ESI) of uranyl nitrate solutions generates a wide variety of positively and negatively charged ions, including complex adducts of uranyl ions with methoxy, hydroxy, and nitrate ligands. In the positive ion mode, ions detected by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry are sensitive to instrumental tuning parameters such as quadrupole operating frequency and trapping time. Positive ions correspond to oligomeric uranyl nitrate species that can be characterized as having a general formula of

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Section: Ion-molecule Reactions In the Gas-phase With D 2 O And Cd 3 supporting

confidence: 53%

Section: Ion-molecule Reactions In the Gas-phase With D 2 O And Cd 3 mentioning

confidence: 60%

Ions generated from uranyl nitrate solutions by electrospray ionization (ESI) and detected with fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometry

Pasilis

Somogyi

Herrmann

et al. 2006

J. Am. Soc. Mass Spectrom.

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“…Its application to nuclear fuel reprocessing by selective reduction of uranium(VI) to uranium(IV) had been a subject of a number of investigations in the 1970s and 1980s, and uraA C H T U N G T R E N N U N G nium(VI) photoreduction has also been a subject of investigation during the last ten years. [2][3][4][5][6] Uranyl(VI) photochemistry further forms the basis for uranium(VI) detection and determination of its speciation by laser-induced luminescence spectroscopy. [7] Photoreduction and photoinduced luminescence of uranium(VI) are closely related to each other, because in both cases the first process is photoexcitation of uranium(VI) to higher excited states.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence of Uranium(VI): Quenching Mechanism and Role of Uranium(V)

Tsushima¹,

Götz²,

Fahmy³

2010

Chemistry A European J

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The photoluminescence of uranium(VI) is observed typically in the wavelength range 400-650 nm with the lifetime of several hundreds mus and is known to be quenched in the presence of various halide ions (case A) or alcohols (case B). Here, we show by density functional theory (DFT) calculations that the quenching involves an intermediate triplet excited state that exhibits uranium(V) character. The DFT results are consistent with previous experimental findings suggesting the presence of photoexcited uranium(V) radical pair during the quenching process. In the ground state of uranyl(VI) halides, the ligand contributions to the highest occupied molecular orbitals increase with the atomic number (Z) of halide ion allowing larger ligand-to-metal charge transfer (LMCT) between uranium and the halide ion. Consequently, a larger quenching effect is expected as Z increases. The quenching mechanism is essentially the same in cases A and B, and is driven by an electron transfer from the quencher to the UO(2)(2+) entity. The relative energetic stabilities of the triplet excited state define the "fate" of uranium, so that in case A uranium(V) is oxidized back to uranium(VI), while in case B uranium remains as pentavalent.

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“…[14] In our case, hydrogen-atom extraction from the Val314 side chain by the uranyl ion in the excited state is a strong possibility. [14,16] The reaction of the resulting alkyl radical with oxygen could lead to peptide-bond cleavage, as suggested earlier. [6,7] Further studies are in progress to consider these details.…”

Section: +mentioning

confidence: 87%

“…(lifetime = 1.4 ms) [16] should have resulted in quenching constants greater than 10 3 m À1 (k q lifetime). The much smaller value observed here (0.35 m À1 ) indicates that the cleavage results from UO 2 2+ bound to the protein and not from free UO 2 2+ .…”

Section: +mentioning

confidence: 99%

Site‐Selective Photocleavage of Proteins by Uranyl Ions

Duff¹,

Kumar²

2005

Angew Chem Int Ed

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Dedicated to Professor J. C. Scaiano on the occasion of his 60th birthdayThe uranyl ion (UO 2 2+ ) has a high affinity for the phosphate groups of DNA/RNA, [1] and this affinity was exploited to photocleave these biopolymers at the uranyl-binding sites. [2][3][4][5] Earlier success in our laboratory with site-specific photocleavage of proteins by organic molecules [6] and metal complexes [7] led to the idea that photoactive [8] metal-oxo species such as UO 2 2+ should be capable of cleaving proteins with high selectivity. However, even though there is ample evidence to suggest that UO 2 2+ binds to proteins, [9, 10] it is not known if UO 2 2+ can photocleave the peptide backbone. It is also not known if binding of UO 2 2+ at specific sites would result in high selectivity for the protein cleavage. In addition, the ease with which UO 2 2+ can be directed to metal-binding sites on proteins and the activation of the cation at visible wavelengths indicated that this would be a promising approach for footprinting metalbinding sites. In this report, high-affinity binding of UO 2 2+ to proteins and their site-selective photocleavage, with visible light, is demonstrated for the first time.Serum albumin (SA) and transferrin are known to bind UO 2 2+ , [11,12] and these proteins therefore provided good initial targets to test the above approach. Quantitative data on the binding of UO 2 2+ to bovine SA (BSA), however, were lacking; these were obtained from calorimetric and spectroscopic studies. Isothermal titration calorimetry of the addition of a solution of UO 2 2+ (0.5 mm) to BSA (0.1 mm ; see Supporting Information) indicated exothermic binding (Figure 1). Best fits to the data required a two-site binding model [13] and indicated a high-affinity site (binding constant (K b ) of (1.6 AE 0.7) 10 7 m À1 ) with moderate exothermicity (binding enthalpy (DH) of (À4.7 AE 0.7) kcal mol À1 ) and a low-affinity site (K b = 2.8 AE 2.5 10 5 m À1 ) with weak exothermicity (DH = À(1.2AE0.8) kcal mol À1 ). Binding of UO 2 2+ to BSA was also supported by absorption, circular dichroism (CD), and fluorescence studies.The CD spectra, for example, of a mixture of BSA (1 mm) and UO 2 2+ in increasing concentrations (0-0.8 mm) showed the growth of new bands at 440 and 510 nm (Figure 2). These evidences established the binding of UO 2 2+ to BSA. Photocleavage of BSA by UO 2 2+ was achieved by irradiating a mixture of BSA and UO 2 2+ at 420 nm (Figure 3). Three distinct product bands at 35, 33 and 30 kDa were obtained in yields (11 AE 0.5), (4 AE 0.6), and (11 AE 1) % (lane 5), respectively. No photocleavage was noted without UO 2 2+ (lane 3) or without light (lane 4). Photocleavage was observed at wavelengths up to 460 nm, although the yields were lower (data not shown).To demonstrate the general nature of the photocleavage, other proteins such as human SA (HSA), porcine SA (PSA), glucose oxidase, and transferrin were also tested. These are cleaved with high selectivity (see Supporting Information). As negative controls, we also tested the ...

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Deactivation processes of the lowest excited state of [UO2(H2O)5]2+ in aqueous solution

Cited by 52 publications

References 86 publications

Ions generated from uranyl nitrate solutions by electrospray ionization (ESI) and detected with fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometry

Ions generated from uranyl nitrate solutions by electrospray ionization (ESI) and detected with fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometry

Photoluminescence of Uranium(VI): Quenching Mechanism and Role of Uranium(V)

Site‐Selective Photocleavage of Proteins by Uranyl Ions

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