Ln Cations Research Articles

A Series of Lanthanide Coordination Polymers as Luminescent Sensors for Selective Detection of Inorganic Ions and Nitrobenzene.

Seven new lanthanide coordination polymers, namely [Ln(cpt)3H2O)]n(Ln = La (1), Pr (2), Sm (3), Eu (4), Gd (5), Dy (6), and Er (7)), which were synthesized under hydrothermal conditions using 4'-(4-(4-carboxyphenyloxy)phenyl)-4,2':6',4'-tripyridine (Hcpt) as the ligand. The crystal structures of these seven complexes were determined using single-crystal X-ray diffraction, and they were found to be isostructural, crystallizing in the triclinic P1- space group. The Ln(III) ions were nine-coordinated with tricapped trigonal prism coordination geometry. The Ln(III) cations were coordinated by carboxylic and pyridine groups from (cpt)- ligands, forming one-dimensional ring-chain structures. Furthermore, the luminescent properties of complexes 1-7 were investigated using fluorescent spectra in the solid state. The fluorescence sensing experiments demonstrated that complex 4 exhibits high selectivity and sensitivity for detecting Co2+, Cu2+ ions, and nitrobenzene. Moreover, complex 3 shows good capability for detecting Cu2+ ions and nitrobenzene. Additionally, the sensing mechanism was also thoroughly examined through theoretical calculations.

Understanding Europium and Terbium Speciation and Ion Pairing in Carbonate Complexes Using Advanced Spectroscopy Techniques

Lanthanide (Ln) elements are critical materials that are typically extracted/mined together. Their separation by solvent extraction from acidic media is well known; however, there are few studies in basic media with carbonate anions. We investigated the complexation of Eu(III) and Tb(III) carbonates as solids and solutions in alkaline K2CO3, wherein we sought to access a Tb(IV) carbonate complex through ozonolysis. L3‐edge XANES of Eu and Tb carbonate solids, colorless solutions, and a red‐hued Tb solution (obtained by ozonolysis) all showed Ln(III) cations. The absence of evidence for a Tb(IV) complex was confirmed through XAS and EPR analyses, despite the solution exhibiting a deep red color. For solids and solutions, EXAFS results indicate molecular Ln(III)‐carbonato anions. In terms of the Eu(III) carbonate coordination number, the coordination does not change upon dissolution of the solid sample. Furthermore, EXAFS for the solutions revealed evidence for the association of potassium cations with the Ln(III)‐carbonato anions. This direct observation of contact ion pairing by EXAFS at room temperature is rare. The insights into Ln(III) carbonate complexation and solution speciation afforded by XANES‐EXAFS, FT‐IR, and EPR provides perspectives that serve as benchmarks for future computational and experimental efforts focused on caustic‐side solvent extraction of Ln(III) ions.

Programming heterometallic 4f-4f' helicates under thermodynamic control: the circle is complete.

Three non-symmetrical segmental ligand strands L4 can be wrapped around a linear sequence of one Zn2+ and two trivalent lanthanide cations Ln3+ to give quantitatively directional [ZnLn2(L4)3]8+ triple-stranded helicates in the solid state and in solution. NMR speciations in CD3CN show negligible decomplexation at a millimolar concentration and the latter helicate can be thus safely considered as a preorganized C3-symmetrical HHH-[(L43Zn)(LnA)(2-n)(LnB)n]8+ platform in which the thermodynamic properties of (i) lanthanide permutation between the central N9 and the terminal N6O3 binding sites and (ii) exchange processes between homo- and heterolanthanide helicates are easy to access (Ln = La, Eu, Lu). Deviations from statistical distributions could be programmed by exploiting specific site recognition and intermetallic pair interactions. Considering the challenging La3+ : Eu3+ ionic pair, for which the sizes of the two cations differ by only 8%, a remarkable excess (70%) of the heterolanthanide is produced, together with a preference for the formation of the isomer where the largest lanthanum cation lies in the central N9 site ([(La)(Eu)] : [(Eu)(La)] = 9 : 1). This rare design and its rational programming pave the way for the preparation of directional light-converters and/or molecular Q-bits at the (supra)molecular level.

Effects of synthesis conditions on the crystal and local structures of high-entropy oxides Ln[formula omitted]O[formula omitted] (Ln = La-Yb, Y; M = Ti, Zr, Ce)

The synthesis and detailed study of six series of high-entropy complex oxides containing lanthanides (Ln) and transition metals with the general formula Ln2M2O7 (Ln = La-Yb, and Y; M = Ti, Zr, and Ce) with the number of different Ln cations not less than six in each case are reported. The influence of synthesis conditions (types of the Ln3+ and M4+ cations, calcination temperature) used in the synthesis via either coprecipitation or sol–gel method on the crystal and local structures of target materials is comprehensively surveyed. The studies were carried out using a combination of long- (s-XRD), medium- (Raman, FT-IR, SEM-EDS) and short-range (XAFS) sensitive techniques, as well as AES-ICP and STA. It was established that the ratio of the cation radii γ = r̄Ln3+/r̄M4+ is the main factor that determines the type of initially formed crystal structure. In the boundary region (γ∼ 1.42–1.47), the average radius of lanthanide cation (r̄Ln3+), along with the r̄Ln3+/r̄M4+ ratio, also plays a significant role in the type of the resulting crystal structure of the high-entropy lanthanide complex oxides. The presence of inhomogeneity in the distribution of elements in precursors significantly affects the phase composition of the resulting high-entropy oxides. An increase in the calcination temperature promotes not only the occurrence of subsequent phase transitions, but also an increase in the single-phase nature of the resulting high-entropy complex rare-earth oxides. At the same time, the cations included in the composition retain some independence, despite the fact that they occupy one crystallographic position in the resulting crystal structure.

DFT-based investigation of solvation of Nd(III)/Yb(III) cations in room-temperature ionic-liquid

We report a DFT study on the solvation of bare rare-earth (RE) cations [Nd(III) and Yb(III)] in the room-temperature ionic-liquid (RTIL) based on 1,3-dimethyl-imidazolium+, PF6−, [MMI][PF6]. In the present article, we aim to investigate whether the chosen RTIL can preferentially solvate any of the RE cations under study. First, the RTIL binding to the RE cation is studied in the gas phase, and then explored with continuum solvation model employing RTIL parameters. First, we considered the formation of the first solvation shell, where the PF6− anions directly bond with the Ln(III) cation. We then further surrounded the first solvation shell with [MMI]+ cations to form the second solvation shell. The stability of PF6− coordinated complexes is studied by calculating the binding energy values. The number of PF6− anions for both Ln(III) cations starts with three ligands and goes until the maximum binding energy in the RTIL medium is reached. The coordination number and binding modes of PF6− depend on the size of the RE cation. Comparing the binding energy values between the RE cations for the first solvation shell complexes, it is noticed that Yb-complexes have relatively greater binding energy than Nd-complexes. We have further performed a Boltzmann population analysis to find out the most dominant conformer among each category of PF6− coordinated complexes. A study using Natural Population Analysis shows that after complexation with PF6− the charge on the Yb-centers lower to a greater extent than Nd-centers, implying stronger bonding between Yb and PF6−, which is in harmony with the binding energy analysis. Overall, the computational investigation provides an in-depth understanding of the complexation phenomena of RE cations in RTIL, which can be useful for the practical separation of RE cations using RTIL.

Impact of Ln cation on the oxygen ion conductivity of Ln14W4O33 (Ln = Nd, Sm, Gd, Dy, Ho, Er, Tm, Yb) tungstates

Tungstates Ln14W4O33 (Ln = Nd, Sm, Gd, Dy, Ho, Er, Tm, Yb) with a pseudorhombohedral structure have been synthesized by a short high temperature annealing (1450–1600 °С) from mechanically activated mixtures of oxides. The resulting ceramics were studied by X-ray diffraction, Raman and SEM analyses. The conductivity of ceramics was measured by the 4-probe direct current method in dry and wet atmospheres (oxidizing and reducing) and by impedance spectroscopy. In order to estimate the ionic and electronic contributions to the total conductivity, the dependences of the conductivity on the oxygen partial pressure (pO2) were determined at temperatures between 700 and 900 °C. Ln14W4O33 (Ln = Nd, Sm, Gd) tungstates have a wide electrolytic range (10−15–1 atm) above 700 °C. It should be noted that under oxidizing conditions the contribution of hole conductivity is absent in these compounds. Among the pseudorhombohedral phases of Ln14W4O33 (Ln = Nd, Sm, Gd), Nd14W4O33 exhibits the highest oxygen-ion conductivity (4 × 10−4 S/cm at 700 °C). The electrolytic domain of the second half of the REE Ln14W4O33 (Ln = Dy, Ho, Er, Tm, Yb) series becomes narrower (10−10–10−5 atm) and at the same time has a slight slope indicating the presence of impurity electronic charge carriers. Investigations in a reducing atmosphere confirmed that the reduction tendency increases with decreasing lanthanide ionic radius in the Ln14W4O33 tungsten series. The variations of the total conductivity in the series of pseudorhombohedral phases Ln14W4O33 (Ln = Dy, Ho, Er, Tm, Yb) are associated with local changes in the short-range order structure (Raman spectroscopy). When Ln14W4O33 (Ln = Nd, Gd) is exposed to water at room temperature for an extended period of time, the total conductivity decreases due to the diffusion of the Nd and Gd cations into the water.

Correlation between hydration properties and electrochemical performances on Ln cation size effect in layered perovskite for protonic ceramic fuel cells

PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor (TIEC) electrode for protonic ceramic fuel cells (PCFCs). The chemical formula for PrBSCF is AA’B2O5+δ, with Pr (A-site) and Ba/Sr (A’-site) alternately stacked along the c-axis. Due to these structural features, the bulk oxygen ion diffusivity is significantly enhanced through the disorder-free channels in the PrO layer; thus, the A site cations (lanthanide ions) play a pivotal role in determining the overall electrochemical properties of layered perovskites. Consequently, previous research has predominantly focused on the electrical properties and oxygen bulk/surface kinetics of Ln cation effects, whereas the hydration properties for PCFC systems remain unidentified. Here, we thoroughly examined the proton uptake behavior and thermodynamic parameters for the hydration reaction to conclusively determine the changes in the electrochemical performances depending on LnBa0.5Sr0.5Co1.5Fe0.5O5+δ (LnBSCF, Ln=Pr, Nd, and Gd) cathodes. At 500 °C, the quantitative proton concentration of PrBSCF was 2.04 mol% and progressively decreased as the Ln cation size decreased. Similarly, the Gibbs free energy indicated that less energy was required for the formation of protonic defects in the order of PrBSCF < NdBSCF < GdBSCF. To elucidate the close relationship between hydration properties and electrochemical performances in LnBSCF cathodes, PCFC single cell measurements and analysis of the distribution of relaxation time were further investigated.

A Cationic Metal Glue Strategy for Expanding Paramagnetic Hetero-Multinuclear Metal-Oxo Clusters within Polyoxometalate Ligands.

Precise structural design of large hetero-multinuclear metal-oxo clusters is crucial for controlling their large spin ground states and multielectron redox properties for application as a single-molecule magnet (SMM), molecular magnetic refrigeration, and efficient redox catalyst. However, it is difficult to synthesize large hetero-multinuclear metal oxo clusters as designed because the final structures are unpredictable when employing conventional one-step condensation reaction of metal cations and ligands. Herein, we report a "cationic metal glue strategy" for increasing the size and nuclearity of hetero-multinuclear metal-oxo clusters by using lacunary-type anionic molecular metal oxides (polyoxometalates, POMs) as rigid multidentate ligands. The employed method enabled the synthesis of {(FeMn4 )Mn2 Ln2 (FeMn4 )} oxo clusters (Ln=Gd, Tb, Dy, and Lu), which are the largest among previously reported paramagnetic hetero-multinuclear metal-oxo clusters in POMs and showed unique SMM properties. These clusters were synthesized by conjugating {FeMn4 } oxo clusters with Mn and Ln cations as glues in a predictable way, indicating that the "cationic metal glue strategy" would be a powerful tool to construct desired large hetero-multinuclear metal clusters precisely and effectively.

A Cationic Metal Glue Strategy for Expanding Paramagnetic Hetero‐Multinuclear Metal‐Oxo Clusters within Polyoxometalate Ligands

AbstractPrecise structural design of large hetero‐multinuclear metal‐oxo clusters is crucial for controlling their large spin ground states and multielectron redox properties for application as a single‐molecule magnet (SMM), molecular magnetic refrigeration, and efficient redox catalyst. However, it is difficult to synthesize large hetero‐multinuclear metal oxo clusters as designed because the final structures are unpredictable when employing conventional one‐step condensation reaction of metal cations and ligands. Herein, we report a “cationic metal glue strategy” for increasing the size and nuclearity of hetero‐multinuclear metal‐oxo clusters by using lacunary‐type anionic molecular metal oxides (polyoxometalates, POMs) as rigid multidentate ligands. The employed method enabled the synthesis of {(FeMn4)Mn2Ln2(FeMn4)} oxo clusters (Ln=Gd, Tb, Dy, and Lu), which are the largest among previously reported paramagnetic hetero‐multinuclear metal‐oxo clusters in POMs and showed unique SMM properties. These clusters were synthesized by conjugating {FeMn4} oxo clusters with Mn and Ln cations as glues in a predictable way, indicating that the “cationic metal glue strategy” would be a powerful tool to construct desired large hetero‐multinuclear metal clusters precisely and effectively.

SYNTHESIS, GROWTH OF MONOCRYSTALS AND PROPERTIES OF THE COMPOUNDS OF PbLnCuS3 (Ln–La, Nd, Sm, Gd, Dy, Er) TYPE

Quaternary sulfides of the PbLnCuS3 type (Ln–La, Nd, Sm, Gd, Dy, Er) have been obtained either by melting the elements or through furnace charge, 2PbS+Cu2S+Ln2S3 in a graphite crucible placed in a sealed quartz ampoule at a temperature of 1200–1275 K. Monocrystals of PbSmCuS3 and PbGdCuS3 have been grown by mineralization method. The study of X-ray analysis showed that compounds of PbLnCuS3 type crystallize in the orthorhombic singony (а=8.268.20; b=8.848.80; с=7.967.9Å, space group Pmn21). In a series of PbLnCuS3 compounds, the phenomenon of morphotropy manifests itself, which flows from the exchange of the structural type (PbCuSbS3 KZrCuSe3  Eu2CuS2), i.e. when the radius of the cation Ln changes. Their standard thermodynamic functions have been calculated and the temperature dependences of the magnetic susceptibility have been measured

Synthesis and photophysical properties of rare earth (La, Nd, Gd, Y, Ho) complexes with silanediamido ligands bearing a chelating phenylbenzothiazole chromophore

A new silanediamine ligand L2− bearing planar Ph-benzothiazole groups gives complexes [LnL2]− with larger Ln cations (La, Nd, Gd, Y), and [HoLCl2Li(thf)2]. Their luminescence was investigated, and the triplet state energy of the ligand was estimated.

Pyridinium Salts of Dehydrated Lanthanide Polychlorides

The reaction of lanthanide (Ln) chloride hydrates ([Ln(H2O)n(Cl)3]) with pyridine (py) yielded a set of dehydrated pyridinium (py-H) Ln-polychloride salts. These species were crystallographically characterized as [[py-H-py][py-H]2[LnCl6]] (Ln-6; Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) or [[py-H]2[LnCl5(py)]] ((Ln-5; Ln = Tb, Dy, Ho, Er, Tm, Yb, Lu). The Ln-6 metal centers adopt an octahedral (OC-6) geometry, binding six Cl ligands. The -3 charge is off-set by two py-H moieties and a di-pyridinium (py-H-py) ion. For the Ln-5 species, an OC-6 anion is formed by the Ln cation binding a single py and five Cl ligands. The remaining -2 charge is offset by two py-H+ cations that H-bond to the anion. Significant H-bonding occurs between the various cation/anion moieties inducing the molecular stability. The change in structure from the Ln-6 to Ln-5 is believed to be due to the Ln-contraction producing a smaller unit cell, which prevents formation of the py-H-py+ cation, leading to the loss of the H-bonding-induced stability. Based on this, it was determined that the Ln-5 structures only exist when the lattice energy is small. While dehydrated polychloride salts can be produced by simply mixing in pyridine, the final structures adopted result from a delicate balance of cation size, Coulombic charge, and stabilizing H-bonding.

Beyond the ionic radii: A multifaceted approach to understand differences between the structures of LnNbO4 and LnTaO4 fergusonites

Synchrotron X-ray powder diffraction methods have been used to obtain accurate structures of the lanthanoid tantalates, LnTaO4, at room temperature. Three different structures are observed, depending on the size of the Ln cation: P21/c (Ln = La, Pr), I2/a (Ln = Nd-Ho), and P2/c (Ln = Tb-Lu). BVS analysis indicated that TaV is six-coordinate in these structures, with four short bonds and two longer bonds. Synchrotron X-ray powder diffraction methods were also used to observe the impact of Ta doping on the orthoniobates, Ln(Nb1-xTax)O4 (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Ho, Yb, and Lu). Where both the niobate and tantalate oxide were isostructural (fergusonite structure, space group I2/a), complete solid solutions were prepared. In these solid solutions, the unit cell volume decreases as the Ta content increases. The subtle interaction evident between the LnO8 and BO6 sublattices in the fergusonite-type oxides was not observed in the related pyrochlore oxides. A combined synchrotron X-ray and neutron powder diffraction study of the series Ho(Nb1-xTax)O4 was used to determine accurate atomic positions of the anions, and hence, bond lengths. This revealed a change in the (Nb/Ta)-O bond lengths, reflective of the difference in the valence orbitals of Nb(4d) and Ta(5d). Examination of the partial density of states demonstrates differences in the electronics between Nb and Ta, leading to a difference in the bandgap. This study highlights the importance of the long B-O contacts in the fergusonite structures, and its potential impact on the I2/a to I41/a phase transition.

Ln3MBi5 (Ln=Pr, Nd, Sm; M=Zr, Hf): Intermetallics with Hypervalent Bismuth Chains

AbstractWe report five new isostructural compounds in the Ln3MBi5 (Ln=Pr, Nd, Sm; M=Zr, Hf) family, and compare them to the recently reported Sm3ZrBi5 analogue. Ln3MBi5 crystallizes in the P63/mcm space group, hosting the anti‐Hf5Sn3Cu structure type. The one‐dimensional structure consists of hypervalent Bi2− chains and face‐sharing MBi6 octahedra that form chains along the c axis. A framework of Ln3+ cations charge balances and separates the two motifs. The Bi−Bi and M−Bi bond lengths decrease as the Ln cation becomes smaller across the period, but there is almost no difference in either bond length when the identity of M changes, as expected because Zr and Hf have the exact same radii due to lanthanide contraction. We present a structural stability map showing the limits of cation stability in the structure, with La3+ and U3+ as the largest cations and Sm3+ as the smallest cation. X‐ray photoelectron spectra suggest ambiguous valence states in the Ln3MBi5 structure depending on the identity of the M atom. This work further expands the Ln3MBi5 family and sheds new light on how their bonding behavior may vary based on chemical composition.

Lanthanide ions induce DNA compaction with ionic specificity

Lanthanide (Ln) cations exhibit unique properties that include the ability to interact with DNA to form metal–DNA complexes, which are of great interest in medical, biological and nano-technological fields. Both experimental and theoretical studies have not completely addressed the interaction dynamics between lanthanide ions and DNA. The present study investigates the dynamics of the Ln3+–DNA interaction at the level of a single DNA molecule. Different DNA-metal complexes were produced by the addition of the five lanthanide ions, La3+, Ce3+, Pr3+, Tb3+, and Ho3+ to the DNA solutions. The binding dynamics indicated that the lanthanide cations can induce DNA compaction in a concentration and force-dependent manner. Ionic specificity was displayed in the single-molecule interaction dynamics, where, Ho3+ was found to be the most efficient lanthanide to cause DNA compaction, which was verified by the morphological characterization. The DNA molecules in the five Ln3+–DNA complex solutions were restored to their original length with different restoration speeds, by the addition of EDTA, and this further indicated that the Ho3+ ion had the strongest affinity toward DNA. We conclude that counterion correlation cannot solely explain the ion-dependent DNA compaction, and ionic specificity should be considered significant.

Heterobimetallic Ln(III)‐Containing Materials Based on One‐Dimensional Aurophilic Chains of Gold(I) Dithiolate Dimers and Their Vapochromic Response to DMF

AbstractThe synthesis, characterization, X‐ray structures and luminescence of a series of lanthanide coordination polymers containing anionic gold(I) iso‐maleonitriledithiolate units ([Au2(i‐mnt)2]2−; {Au2[S2C=C(CN)2]2}2−) are described. Crystals of (nBu4N)Ln(DMF)8[Au2(i‐mnt)2]2 (Ln=Gd, Tb, Eu) contain 1‐D aurophilic chains of [Au2(i‐mnt)2]2− units and DMF‐saturated Ln(III) cations. The Ln=Gd and Tb systems are emissive, with λmax=596 and 625 nm respectively, attributable to the aurophilic chains. The luminescence intensities and emission energies qualitatively correlate to the local concentration of DMF vapour, where emission‐quenched (nBu4N)Ln(DMF)5[Au2(i‐mnt)2]2 is formed upon sample removal from a DMF atmosphere for 24 hours; the emissive species was regenerated by exposure to fresh DMF vapour. A similar turn‐on luminescence effect was also observed when a quenched sample of (nBu4N)Tb(DMF)5[Au2(i‐mnt)2]2 powder was exposed to pyridine, resulting in emission with λmax=625 nm. Structure‐property correlations show that the emission maximum is influenced not only by the intermolecular Au−Au distances but also by a combination of the Au−Au−Au angles and other geometric factors in the [Au2(i‐mnt)2] units.

Interaction of the Fungal Metabolite Harzianic Acid with Rare-Earth Cations (La3+, Nd3+, Sm3+, Gd3+).

Rare-earth elements are emerging contaminants of soil and water bodies which destiny in the environment and effects on organisms is modulated by their interactions with natural ligands produced by bacteria, fungi and plants. Within this framework, coordination by harzianic acid (H2L), a Trichoderma secondary metabolite, of a selection of tripositive rare-earth cations Ln3+ (Ln3+ = La3+, Nd3+, Sm3+, and Gd3+) was investigated at 25 °C, and in a CH3OH/0.1 M NaClO4 (50/50 w/w) solvent, using mass spectrometry, circular dichroism, UV–Vis spectrophotometry, and pH measurements. Experimental data can be satisfactorily explained by assuming, for all investigated cations, the formation of a mono-complex (LnL+) and a bis-complex (LnL2−). Differences were found between the formation constants of complexes of different Ln3+ cations, which can be correlated with ionic radius. Since gadolinium is the element that raises the most concern among lanthanide elements, its effects on organisms at different levels of biological organization were explored, in the presence and absence of harzianic acid. Results of ecotoxicological tests suggest that harzianic acid can decrease gadolinium biotoxicity, presumably because of complex formation with Gd3+.

Giant Ln 30 -Cluster-Embedded Polyoxotungstate Nanoclusters with Exceptional Proton-Conducting and Luminescent Properties

Giant Ln ₃₀ -Cluster-Embedded Polyoxotungstate Nanoclusters with Exceptional Proton-Conducting and Luminescent Properties

Growth, crystal structure, and properties of the Li3Ba2Ln3(MoO4)8 (Ln = Er, Tm) molybdates

The compounds Li3Ba2Ln3(MoO4)8 (Ln = Er, Tm) have been obtained by the high-temperature flux technique using the slow cooling method. Crystals grown spontaneously were used to characterize the materials and investigate their properties using X-ray diffraction (XRD), Raman spectroscopy, and magnetic measurements. Single crystal structures were solved and refined in the monoclinic space group C2/c. Lattice dimensions are a = 5.1935, b = 12.6364, c = 19.1022 Å, β = 91.399° for Er-based triple molybdate (pink crystals) and a = 5.1846, b = 12.5766, c = 19.1557 Å, β = 91.525° for Tm-molybdate (green crystals). The Ln cations, mainly at general position 8f, are coordinated by eight oxygen atoms and adopt a distorted antiprismatic geometry. The distribution of atoms over the three cationic sites is discussed comparatively to literature reports. Unpolarized Raman characterization supports both the disordered cation distribution, and the distortion of the MoO4 units. From the magnetic susceptibility measurements, it is found that the two triple molybdates follow a Curie-Weiss law in the 10–300 K domain, with a negative paramagnetic temperature θCW. The antiferromagnetic character is highlighted by the field-dependent magnetization curves.

Theoretical Study of Effects of Solvents, Ligands, and Anions on Separation of Trivalent Lanthanides and Actinides.

Due to its associated low CO2 emissions, nuclear energy production is rapidly growing. In this context, the treatment of high-level liquid waste (HLLW) of nuclear plants is of high concern to both scientific and industrial communities. Specifically, the separation of An(III) and Ln(III) cations when processing nuclear fuel is a vitally important, yet challenging, step within HLLW because An(III) and Ln(III) have similar chemical properties in solution. To guide the choice of relevant ligands, anions, and solvents for this separation step, in this work, we calculate and compare the free energy of formation of different Am(III) and Eu(III) complexes (which are typical and important An(III) and Ln(III) cation examples), involving two different ligands and three different counter ions in four different solvents. Based on our calculations, we predict that the chosen solvent is a key factor in the extraction of Am(III) and Eu(III) in treatment of HLLW. This study supports a systematic, computation-assisted screening of solvents and extractive ligands with counter anions as a proficient method to optimize the separation of Ln(III) and An(III).