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![Comparison of the first eight Es L3-edge XANES scans collected for [EsIII(HOPO)]⁻ at 77 K
The oldest scan is shown at the top and the newest at the bottom, as indicated by the black arrow. Each scan required about 40 min. Scans are offset for clarity.](publication/349018256/figure/fig5/AS:987773683122185@1612515006213/Comparison-of-the-first-eight-Es-L3-edge-XANES-scans-collected-for-EsIIIHOPO-at.jpg)
Comparison of the first eight Es L3-edge XANES scans collected for [EsIII(HOPO)]⁻ at 77 K The oldest scan is shown at the top and the newest at the bottom, as indicated by the black arrow. Each scan required about 40 min. Scans are offset for clarity.
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![Comparison of XANES data for [AnIII(HOPO)]⁻ complexes
AmIII, CmIII and...](publication/349018256/figure/fig1/AS:987773674725376@1612515004906/Comparison-of-XANES-data-for-AnIIIHOPO-complexes-AmIII-CmIII-and-CfIII-spectra-were_Q320.jpg)
![Raw EXAFS data for [EsIII(HOPO)]⁻
Data are shown as in Fig. 2b, but...](publication/349018256/figure/fig3/AS:987773683130368@1612515006021/Raw-EXAFS-data-for-EsIIIHOPO-Data-are-shown-as-in-Fig-2b-but-extended-beyond-the_Q320.jpg)
![M–O bond distance R versus kmax for [MIII(HOPO)]⁻ actinide...](publication/349018256/figure/fig4/AS:987773683105792@1612515006098/M-O-bond-distance-R-versus-kmax-for-MIIIHOPO-actinide-complexes-These-MIIIHOPO_Q320.jpg)
The transplutonium elements (atomic numbers 95–103) are a group of metals that lie at the edge of the periodic table. As a result, the patterns and trends used to predict and control the physics and chemistry for transition metals, main-group elements and lanthanides are less applicable to transplutonium elements. Furthermore, understanding the pro...
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Highly charged ions of heavy actinides from uranium to einsteinium are studied theoretically to find optical transitions sensitive to the variation of the fine structure constant. A number of promising transitions have been found in ions with ionisation degree $\sim$~10. All these transitions correspond in single-electron approximation to the $6p$...
Citations
... The use of actinide targets in combination with intense heavy ion beam irradiation has transformed superheavy element (SHE) research, significantly expanding the periodic table by adding five new heaviest elements since 2012 [1][2][3]. These advances have been accomplished using the "hot fusion" technique [4], where heavy actinide targets, typically 243 Am, 240,242,244 Pu, 245,248 Cm, 249 Bk, and 249 Cf, are bombarded with 48 Ca beams at large accelerator facilities, creating compound nuclei that decay to superheavy nuclei with half-lives ranging up to many hours for lower proton numbers (Z) to a e-mail: robertojb@ornl.gov (corresponding author) hundreds of microseconds for higher Zs. ...
... Heavy actinides are the highest Z target materials available, making them attractive for the synthesis of SHEs (i.e., elements with atomic numbers of 104 or greater). For a given superheavy element, higher Z targets and the neutron-rich 48 Ca projectile lead to more asymmetric nuclear reactions with correspondingly lower Coulomb barriers in comparison to the cold fusion reactions with 208 Pb and 209 Bi targets and beams heavier than 48 Ca. Heavy actinides also have higher neutron numbers, and 48 Ca projectiles provide additional excess neutrons. ...
... Heavy actinides are the highest Z target materials available, making them attractive for the synthesis of SHEs (i.e., elements with atomic numbers of 104 or greater). For a given superheavy element, higher Z targets and the neutron-rich 48 Ca projectile lead to more asymmetric nuclear reactions with correspondingly lower Coulomb barriers in comparison to the cold fusion reactions with 208 Pb and 209 Bi targets and beams heavier than 48 Ca. Heavy actinides also have higher neutron numbers, and 48 Ca projectiles provide additional excess neutrons. ...
The use of heavy actinide targets, including ²⁴³ Am, 240,242,244 Pu, 245,248 Cm, ²⁴⁹ Bk, and ²⁴⁹ Cf, irradiated by intense heavy ion beams of ⁴⁸ Ca has resulted in a significant expansion of the periodic table since 2000, including the discovery of five new heaviest elements and more than 50 new isotopes. These actinide materials can only be produced by intense neutron irradiation in very high flux reactors followed by chemical processing and purification in specialized hot cell facilities available in only a few locations worldwide. This paper reviews the reactor production of heavy actinides, the recovery and chemical separation of actinide materials, and the preparation of actinide targets for superheavy element experiments. The focus is on ²⁴⁸ Cm, ²⁴⁹ Bk, mixed ²⁴⁹⁻²⁵¹ Cf, and ²⁵⁴ Es, including current availabilities and new production processes. The impacts of new facilities, including the Superheavy Element Factory at Dubna, accelerator and separator upgrades at RIKEN, and proposed upgrades to the High Flux Isotope Reactor at Oak Ridge are also described. Examples of recent superheavy element research are discussed as well as future opportunities for superheavy research using actinide targets.
... Handling of volatile alpha emitters requires rigorous safety precautions, and as a result, experimental work even with small quantities of radium compounds is challenging, as is the case for other highly radioactive elements. 4,5 The high radiotoxicity of radium and its decay products requires an understanding of its migration in the environment from technologically enhanced naturally occurring radioactive materials. Moreover, in 2013, a 223 Ra 2+ (t 1/2 = 11.43 days) saline solution (trademark Xofigo © ) was approved by the U.S. Food and Drug Administration and later by the European Medicines Agency for treatment of patients with castrationresistant prostate carcinomas, symptomatic bone metastases, and no known visceral metastatic disease. ...
... To the best of our knowledge, an experimentally determined RaCO 3 solubility product has never been reported in the literature, although an indication that the solubility of RaCO 3 is significantly higher than that of witherite was first given by Nikitin 15 in 1937. Nikitin performed the following experiment: 100 mL of a solution containing 2 g of (NH 4 ) 2 CO 3 , 5 g of NH 4 Cl, and 10 mL of concentrated NaOH was added to 40 mL of a pure concentrated radium solution. The formed precipitate was filtered and a mixture of HCl and H 2 SO 4 was added to the filtrate to precipitate RaSO 4 . ...
... However, in this work, witherite was synthesized using the same method as Ra(Ba)CO 3 and a typical orthorhombic witherite crystal structure was obtained. This indicates that the possible presence of small amounts of SO 4 2− had a negligible influence on the crystal structure of the obtained Ra(Ba)CO 3 phase. Moreover, it can be shown that the synthesis of nonorthorhombic BaCO 3 , 37,38,40,42 SrCO 3 ,42 and PbCO 3 65,80 requires high pressures and temperatures, far above 250°C. ...
Radium-226 carbonate was synthesized from radium-barium sulfate (226Ra0.76Ba0.24SO4) at room temperature and characterized by X-ray powder diffraction (XRPD) and extended X-ray absorption fine structure (EXAFS) techniques. XRPD revealed that fractional crystallization occurred and that two phases were formed─the major Ra-rich phase, Ra(Ba)CO3, and a minor Ba-rich phase, Ba(Ra)CO3, crystallizing in the orthorhombic space group Pnma (no. 62) that is isostructural with witherite (BaCO3) but with slightly larger unit cell dimensions. Direct-space ab initio modeling shows that the carbonate oxygens in the major Ra(Ba)CO3 phase are highly disordered. The solubility of the synthesized major Ra(Ba)CO3 phase was studied from under- and oversaturation at 25.1 °C as a function of ionic strength using NaCl as the supporting electrolyte. It was found that the decimal logarithm of the solubility product of Ra(Ba)CO3 at zero ionic strength (log10 Ksp0) is -7.5(1) (2σ) (s = 0.05 g·L-1). This is significantly higher than the log10 Ksp0 of witherite of -8.56 (s = 0.01 g·L-1), supporting the disordered nature of the major Ra(Ba)CO3 phase. The limited co-precipitation of Ra2+ within witherite, the significantly higher solubility of pure RaCO3 compared to witherite, and thermodynamic modeling show that the results obtained in this work for the major Ra(Ba)CO3 phase are also applicable to pure RaCO3. The refinement of the EXAFS data reveals that radium is coordinated by nine oxygens in a broad bond distance distribution with a mean Ra-O bond distance of 2.885(3) Å (1σ). The Ra-O bond distance gives an ionic radius of Ra2+ in a 9-fold coordination of 1.545(6) Å (1σ).
... Beyond Cm, the available quantities become small, but recent work has shown that the concept of delocalization under pressure may be too simple of a picture. Examples are pressure work on Cf and spectroscopy work on Es (Carter et al., 2021), both of which use SR techniques. ...
... Current XAS experiments at state-of-the-art spectrometers have been extended to the heaviest actinides available in macroscopic quantities, as recently demonstrated in a study of a coordination complex of 254 Es that used less than 200 nanograms of this highly radioactive isotope (half-life of ∼275.7 days) (Carter et al., 2021). XAS techniques, in combination with other chemical physics methods, are also assuming growing importance in the nuclear toxicology field and are enabling the development of effective actinide decorporation agents with high complexation affinity, high tissue specificity, and low biological toxicity (Ye et al., 2021;Zurita et al., 2021Zurita et al., , 2022. ...
... An example of the power of the technique was given by Clark, Janecky, and Lane (2006). The main reason for its success is that the actinides, with so many electrons, give a strong signal, so small quantities can be successfully examined (Carter et al., 2021). For the most part, EXAFS tackles materials that are of interest to chemistry and materials science problems concerning nuclear fuel and nuclear waste disposal (Richmann et al., 2001;Hubert et al., 2006;Walter et al., 2008;Nastren et al., 2009;Degueldre et al., 2011Degueldre et al., , 2013Gaona et al., 2013;Prieur et al., 2013;Ding et al., 2021), molten salts (Volkovich et al., 2005;Smith et al., 2019), and extraction chemistry (Antonio et al., 2001;Bolvin et al., 2001;Skanthakumar et al., 2007;Ikeda-Ohno et al., 2008;Boubals et al., 2017;Ferrier et al., 2018;Bhattacharyya and Mohapatra, 2019). ...
Research on actinide materials, both basic and applied, has been greatly advanced by the general techniques available from high-intensity photon beams from x-ray synchrotron sources. The most important single reason is that such x-ray sources can work with minute (e.g., microgram) samples, and at this level the radioactive hazards of actinides are significantly reduced. The form and encapsulation procedures used for different techniques are discussed, followed by the basic theory for interpreting the results. To demonstrate the potential of synchrotron radiation techniques for the study of lattice and electronic structure, hybridization effects, multipolar order, and lattice dynamics in actinide materials, a selection of x-ray diffraction, resonant elastic x-ray scattering, x-ray magnetic circular dichroism, resonant and nonresonant inelastic scattering, dispersive inelastic x-ray scattering, and conventional and resonant photoemission experiments are reviewed.
... Ein Team um Abergel und Kozimor in Berkeley und Los Alamos in den USA hat diese Frage kürzlich beantwortet, indem es einen Einsteiniumkomplex mit 175 Nanogramm 254 Es synthetisiert und charakterisiert hat. 6) Neben der geringen Menge verfügbaren Materials ist eine weitere Herausforderung die im Vergleich zu den früheren Actinoiden kurze Halbwertszeit von 276 Ta ...
Den meisten Menschen sind die Actinoide lediglich als Elemente in Kernkraftwerken bekannt. Doch seit einigen Jahren werden Koordinationsverbindungen der verschiedenen Actinoide auch in Laboren hergestellt und untersucht.
... These highly symmetric clusters are members of a more general isoelectronic family of closed-shell, M@Au 12 clusters (where M is neutral -Mo,Wor a d 6 ion like V -, Nb -, Taor Re þ ) [80,81] for which the 18 electrons filling the highest bonding orbitals of the cluster come from the [(n-1)d, ns] valence orbitals of the encapsulated metal and from the 6s orbitals of the 12 peripheral gold atoms. Other charged isoelectronic members of this family of endohedral gold clusters [82] are homometallic like the idealized icosahedral [Au@Au 12 ] 5þ naked ion studied by Mingos [83] (later isolated as [Au@Au 12 (PPhMe 2 ) 10 Cl 2 ](PF 6 ) 3 ) [84]) or heterometallic like [Pd@Au 12 ] 4þ , experimentally observed as [Pd@Au 12 (PPh 3 ) 6 (dppe) 4 Cl 4 ] [85]. According to the above interpretation of the electronic structure, the closed-shell [M@Au 12 ] icosahedral clusters could be also described in the framework of closed-shell superatoms, that is, molecular clusters with atom-like one-particle electronic levels, whose stability is associated with "magic" electron counts (2, 8, 18, 20, 34 … ) [86,87]. ...
... There, 261 Rf (t 1/2 ¼ 68 s) atoms along with 169 Hf (t 1/2 ¼ 3.24 min) were co-precipitated with samarium hydroxide in basic solutions (aqueous NH 3 or NaOH) and their precipitates analyzed. Comparisons between the behavior of Rf with that of its lighter homologues Zr (known from previous experiments) and Hf showed that Rf does not coordinate strongly with NH 3 , but forms a hydroxide (co)precipitate that is expected to be Rf(OH) 4 . From the study it was [89], oblate C s -e in ref. [90], O h in ref. [91]. ...
... Calculated 6d covalent radii compared to 5d ones (groups[4][5][6][7][8][9][10][11][12]. Trends for single-bond (diamonds) vs. triple-bond radii (open squares). ...
Transition elements of the seventh period (104 ≤ Z ≤ 112) in the periodic table are definitely relativistic elements. Even their "normal" periodic behavior has an explanation requiring direct and indirect relativistic effects plus increasing spin-orbit couplings. The chemistry of these nine (or ten, depending on conventions for group 3 composition) radioactive artificial elements forming the fourth d-series is rather limited due to their extremely scarce availability and very short lifetimes. This perspective article gives a short outline of the most recent theorethical and experimental studies on the chemical behavior of these elements which at times appear quite ordinary but could deserve less predictable outcomes.
... Y 3+ (log β YL = 20.76)) [84], Hf 4+ and Zr 4+ (log β ML > 42, complexes stable between pH 10 and 10 M HCl) [85], as well as a coordination study (X-ray absorption spectroscopy-XAS, luminescence measurements) with the heaviest element (einsteinium) that can be generated in quantities that enable classical macroscale studies have been performed [86]. Complexation studies of L28 with Eu 3+ , Zr 4+ and Th 4+ (log β EuL = 29.65, ...
Hydroxypyridinones (HPs) are recognized as excellent chemical tools for engineering a diversity of metal chelating agents, with high affinity for hard metal ions, exhibiting a broad range of activities and applications, namely in medical, biological and environmental contexts. They are easily made and functionalizable towards the tuning of their pharmacokinetic properties or the improving of their metal complex thermodynamic stabilities. In this review, an analysis of the recently published works on hydroxypyridinone-based ligands, that have been mostly addressed for environmental applications, namely for remediation of hard metal ion ecotoxicity in living beings and other biological matrices is carried out. In particular, herein the most recent developments in the design of new chelating systems, from bidentate mono-HP to polydentate multi-HP derivatives, with a structural diversity of soluble or solid-supported backbones are outlined. Along with the ligand design, an analysis of the relationship between their structures and activities is presented and discussed, namely associated with the metal affinity and the thermodynamic stability of the corresponding metal complexes.
... Cependant, même avec le bon modèle structural, si la gamme des oscillations en k considérée est trop faible, l'ajustement obtenu sera entaché de fortes incertitudes. 108 Enfin, plus le nombre de chemins de diffusion indépendant i utilisé est important, plus le nombre de paramètres indépendants NR,i, Ri et σ 2 i sera grand. Ainsi, pour un même spectre, des structures différentes pourront fournir des ajustements acceptables. ...
Les clusters d’An(IV) sont des molécules à plusieurs centres métalliques reliés entre eux par des groupes oxo et/ou hydroxo en solution aqueuse (le ceur). Ces espèces se forment en présence d’eau par des réactions de condensation, et sont stabilisées par des ligands organiques ou inorganiques (en surface). Si les structures des clusters sont souvent décrites à l’état solide, elles le sont beaucoup moins en solution. La plupart des clusters observés en solution sont des clusters hexamèriques à géométrie octaédrique, complexés à des ligands à fonction carboxylate. Si quelques données existent pour les clusters hexamériques de Th(IV), U(IV) et de Np(IV) en solution, très peu d’informations sont rapportées sur le Pu(IV). Les données thermodynamiques et cinétiques sur la formation des clusters en solution sont rares. Il en résulte que les clusters ne sont pas pris en compte dans les modèles de spéciation. L’objectif de la thèse est l’étude en solution des clusters de Pu(IV) en présence d’un ligand carboxylate simple, le ligand acétate.Afin d’identifier l’ensemble des espèces susceptibles de se former en solution, le Pu(IV) en présence d’acétate a d’abord été caractérisé par spectroscopie d’absorption Vis-NIR. Huit espèces différentes ont pu être identifiées par spectroscopie Vis-NIR : trois cations aquo (Pu3+, Pu4+ et PuO22+) et cinq espèces d’acétate de Pu(IV). Ces cinq espèces ont ensuite été caractérisées en couplant des approches expérimentales (Vis-NIR, EXAFS et ESI-MS) et théorique par calcul de chimie quantique (DFT). Le cluster hexamérique octaédrique Pu6O4(OH)4(AcO)12(H2O)12 a été identifié en solution. Cette espèce était la structure manquante des clusters hexamèrique An6O6(OH)4(AcO)12 des An(IV). Les quatre autres espèces qui l’accompagnent sont proposées comme étant des complexes « classiques » monomériques. Connaissant les espèces d’acétates de Pu(IV) formées en solution, leurs fractions ont pu être évaluées par déconvolution et reportées sur un diagramme de distribution des espèces en pL.
... Over the past decade there has been a surge in interest in the coordination chemistry of trivalent and tetravalent transuranic elements due to the distinctive chemical properties of the actinides, increased availability of materials, and improvements in instrumentation development and data processing (Carter, Pallares et al., 2020), particularly for X-ray absorption spectroscopy (XAS) and diffraction techniques (Galbis et al., 2010;Cary et al., 2015;Ferrier et al., 2017;Kelley et al., 2018;Mü ller et al., 2021;Jones et al., 2021). Recent highlights of these efforts include the first crystal structure of Bk(III) (Silver et al., 2016), stabilization of Bk(IV) in aqueous solution (Deblonde et al., 2017), measurement of the first bond distance with Es(III) (Carter, Shield et al., 2021), and a significant improvement in our understanding of how covalency and heterogeneity affect 5f-orbital bonding (Allred et al., 2015;Cross et al., 2017;Kelley et al., 2017;Su et al., 2018;Stein et al., 2019;Wilson et al., 2020;Bessen et al., 2021). Even with these advances, transuranic coordination chemistry remains largely underdeveloped, and there is a need to further delineate trends in structure, bonding, and periodicity, as well as evaluate metal-ion redox stability under a range of conditions. ...
... In addition, they have also been shown to be effective in vivo decorporation agents of trivalent and tetravalent actinides (Gorden et al., 2003;Kullgren et al., 2013;Captain et al., 2016;Abergel, 2017;Ricano et al., 2019;Arnedo-Sanchez et al., 2021;Pallares et al., 2021). Exemplary in these efforts is the octadentate chelator 3,4,3-LI(1,2-HOPO), denoted 343-HOPO hereafter, which has been studied with a range of trivalent and tetravalent p-, d-and f-block metals (Abergel et al., 2009;Sturzbecher-Hoehne et al., 2011;Deblonde et al., 2013Deblonde et al., , 2017Deblonde, Lohrey et al., 2018;Carter, Deblonde et al., 2020;Carter, Shield et al., 2021). In both coordination chemistry and in vivo systems, there are significant indications that 343-HOPO chelation-driven redox chemistry is possible (Xu et al., 2000;Deblonde et al., 2013Deblonde et al., , 2017Deblonde et al., , 2019Carter et al., 2018;Carter, Smith et al., 2020, wherein oxidation or reduction of the metal ions are induced depending on redox couple accessibility and complexation thermodynamics. ...
... Herein, we detail two additional examples of reductive decomposition of tetravalent plutonium and berkelium complexes during L III -edge XAS experiments, which are likely the result of radiolysis within the sulfonic acid buffer matrices induced from the intense high-energy X-ray beam. Although we recently used solution-state XAS methodologies to characterize both trivalent and tetravalent aqueous actinide systems Kelley et al., 2018;Carter, Smith et al., 2020Carter, Shield et al., 2021), we have not done so with redox-active ligands, such as 343-HOPO, and metals with an accessible +IV/+III redox couple. Plutonium and berkelium are two transuranic actinides that meet these criteria, with standard +IV/+III redox couples of 0.97 and 1.60 V (in 1 M HClO 4 versus NHE) for Pu and Bk, respectively (Boukhalfa et al., 2007;Antonio et al., 2002). ...
The solution-state interactions of plutonium and berkelium with the octadentate chelator 3,4,3-LI(1,2-HOPO) (343-HOPO) were investigated and characterized by X-ray absorption spectroscopy, which revealed in situ reductive decomposition of the tetravalent species of both actinide metals to yield Pu(III) and Bk(III) coordination complexes. X-ray absorption near-edge structure (XANES) measurements were the first indication of in situ synchrotron redox chemistry as the Pu threshold and white-line position energies for Pu-343-HOPO were in good agreement with known diagnostic Pu(III) species, whereas Bk-343-HOPO results were found to mirror the XANES behavior of Bk(III)-DTPA. Extended X-ray absorption fine structure results revealed An—OHOPO bond distances of 2.498 (5) and 2.415 (2) Å for Pu and Bk, respectively, which match well with bond distances obtained for trivalent actinides and 343-HOPO via density functional theory calculations. Pu(III)- and Bk(III)-343-HOPO data also provide initial insight into actinide periodicity as they can be compared with previous results with Am(III)-, Cm(III)-, Cf(III)-, and Es(III)-343-HOPO, which indicate there is likely an increase in 5f covalency and heterogeneity across the actinide series.
... In ref116, the structures were optimized with ADF/PBE/TZ2P and a COSMO solvation model for an aqueous and proteinlike environment. As seen in the bottom right panel ofFigure 2, the calculated An−O bond lengths in the [An(HOPO)] − (An = Am, Cm, Cf, Es) complexes matched extended X-ray absorption fine structure (EXAFS) data within 0.04 Å.143 ...
... Beyond Cm, the available quantities become very small, but recent work has shown that the concept of de-localization under pressure may be too simple a picture. Examples are pressure work on Cf (Heathman et al., 2013) and spectroscopy work on Es (Carter et al., 2021), both using synchrotron radiation techniques. ...
... This body of experimental work stimulated the construction of dedicated beamlines, such as CAT-ACT at ANKA (Dardenne et al., 2009;Zimina et al., 2017) and ROBL-II at ESRF (Scheinost et al., 2021). Today, XAS experiments at state-ofthe-art spectrometers have been extended to the heaviest actinides available in macroscopic quantities, as recently demonstrated by a study of a coordination complex of 254 Es that used less than 200 ng of this highly radioactive isotope (half-life of $ 275.7 days) (Carter et al., 2021). ...
By reviewing a selection of X-ray diffraction (XRD), resonant X-ray scattering (RXS), X-ray magnetic circular dichroism (XMCD), resonant and non-resonant inelastic scattering (RIXS, NIXS), and dispersive inelastic scattering (IXS) experiments, the potential of synchrotron radiation techniques in studying lattice and electronic structure, hybridization effects, multipolar order and lattice dynamics in actinide materials is demonstrated.
