Enrique R Batista

Los Alamos National Laboratory | LANL

Identifying improved and sustainable alternatives to “classic” separation techniques is an active research field due to its potential widespread impact in fundamental and applied chemistry. As basic purification methodologies, like liquid–liquid extraction, undergo continuous refinement by chemists and engineers, identifying new conditions that out...

The lanthanide elements are crucial components in numerous technologies, yet their industrial production through liquid-liquid extraction continues to be economically and environmentally costly due to the challenge of separating elements with similar physico-chemical properties. While computational ligand screening has shown promise towards discove...

Density functional tight binding (DFTB) models for f-element species are challenging to parametrize owing to the large number of adjustable parameters. The explicit optimization of the terms entering the semiempirical DFTB Hamiltonian related to f orbitals is crucial to generating a reliable parametrization for f-block elements, because they play i...

We present a hybrid semi-empirical density functional tight binding (DFTB) models with a machine learning neural network potential as a correction to the repulsion term. This hybrid model, termed MLTB, employs the standard self-consistent charge (SCC) DFTB formalism as the baseline, enhanced by the HIP-NN potentials as an effective many-body correc...

Neptunium can exist in multiple oxidation states, including the rare and poorly understood heptavalent form. In this work, we monitored the formation of heptavalent neptunium [Np(VII)O4(OH)2]³⁻ during ozonolysis of aqueous MOH (M=Li, Na, K) solutions using a combined experimental and theoretical approach. All experimental reactions were closely mon...

The M4,5-edge high energy resolution X-ray absorption near-edge structure (HR-XANES) spectra of actinyls offer valuable insights into the electronic structure and bonding properties of heavy-element complexes. To conduct a comprehensive spectral analysis, it is essential to employ computational methods that accurately account for relativistic effec...

Numerous technologies—with catalytic, therapeutic, and diagnostic applications—would benefit from improved chelation strategies for heavy alkaline earth elements: Ra ²⁺ , Ba ²⁺ , and Sr ²⁺ . Unfortunately, chelating these metals is challenging because of their large size and weak polarizing power. We found 18-crown-6-tetracarboxylic acid ( H 4 COCO...

A template methodology was employed as an entryway into diastereopure U( iv ) and Np( iv ) organometallic complexes, and the 5f orbital contributions to bonding were determined.

The undeniable importance of nanoparticles has led to vast efforts, in many fields of science, to understand their chemical and physical properties. In this paper, the morphology dependence of f-element nanoparticles is correlated to the oxygen environment and the type and coverage of capping ligands. This dependence was evaluated by first-principl...

Understanding the fundamental chemistry of soft N,S-donor ligands with actinides across the series is critical for separation science toward sustainable nuclear energy. This task is particularly challenging when the ligands are redox active. We herein report a series of actinyl complexes with a N,S-donor redox-active ligand that stabilizes differen...

Modern molten salt reactor design and the techniques of electrorefining spent nuclear fuels require a better understanding of the chemical and physical behavior of lanthanide/actinide ions with different oxidation states dissolved in various solvent salts. The molecular structures and dynamics that are driven by the short-range interactions between...

Rare-earth and actinide complexes are critical for a wealth of clean-energy applications. Three-dimensional (3D) structural generation and prediction for these organometallic systems remains a challenge, limiting opportunities for computational chemical discovery. Here, we introduce Architector, a high-throughput in-silico synthesis code for s-, p-...

The activation of chalcogen-chalcogen bonds using organometallic uranium complexes has been well documented for S-S, Se-Se, and Te-Te bonds. In stark contrast, reports concerning the ability of a uranium complex to activate the O-O bond of an organic peroxide are exceedingly rare. Herein, we describe the peroxide O-O bond cleavage of 9,10-diphenyla...

Neptunium makes up the largest percentage of minor actinides found in spent nuclear fuel, yet separations of this element have proven difficult due to its rich redox chemistry. Developing new reprocessing techniques should rely on understanding how to control the Np oxidation state and its interactions with different ligands. Designing new ligands...

Spin-orbit coupling (SOC) is an important driving force in photochemistry. In this work, we develop a perturbative spin-orbit coupling method within the linear response time-dependent density function theory framework (TDDFT-SO). A full state interaction scheme, including singlet-triplet and triplet-triplet coupling, is introduced to describe not o...

Ammonia (NH3) is one of the basic chemicals in artificial fertilizers and a promising carbon-free energy storage carrier. Its industrial synthesis is typically realized via the Haber−Bosch process using traditional iron-based catalysts. Developing advanced catalysts that can reduce the N2 activation barrier and make NH3 synthesis more efficient is...

The brightness of electron beams emitted from photocathode sources plays a critical role in determining the performance of x-ray free-electron lasers and ultrafast electron-diffraction applications. In order to achieve the maximum brightness, the electrons need to be emitted from a photocathode with the lowest-possible mean transverse energy (MTE)....

Advancing the field of chemical separations is important for nearly every area of science and technology. Some of the most challenging separations are associated with the americium ion Am(III) for its extraction in the nuclear fuel cycle, 241Am production for industrial usage, and environmental cleanup efforts. Herein, we study a series of extracta...

Molten salts have found use as solvents in numerous applications including nuclear reactors, batteries, and the extraction and purification of various metals. Unfortunately, understanding of the chemistry of molten salt solutions is limited. In this presentation we explore the use of molten salts as a testbed for understanding both outer and inner...

Developing chelators that strongly and selectively bind rare-earth elements (Sc, Y, La, and lanthanides) represents a longstanding fundamental challenge in inorganic chemistry. Solving these challenges is becoming more important because of increasing use of rare-earth elements in numerous technologies, ranging from paramagnets to luminescent materi...

The molecular tetravalent oxidation state for praseodymium is observed in solution via oxidation of the anionic trivalent precursor [K][Pr3+(NP(1,2-bis-tBu-diamidoethane)(NEt2))4] (1-Pr(NP*)) with AgI at -35 °C. The Pr4+ complex is characterized in solution via cyclic voltammetry, UV-vis-NIR electronic absorption spectroscopy, and EPR spectroscopy....

A method to explore head‐to‐head ϕ back‐bonding from uranium f‐orbitals into allyl π* orbitals has been pursued. Anionic allyl groups were coordinated to uranium with tethered anilide ligands, then the products were investigated by using NMR spectroscopy, single‐crystal XRD, and theoretical methods. The (allyl)silylanilide ligand, N‐((dimethyl)prop...

Accurate modeling of the complex electronic structure of actinide complexes requires full inclusion of relativistic effects. In this study, we examine the effect of explicit inclusion of spin-orbit coupling (SOC) versus scalar relativistic effects on the predicted spectra for heavy-element complexes. In this study, we employ a relativistic two-comp...

Californium (Cf) is currently the heaviest element accessible above microgram quantities. Cf isotopes impose severe experimental challenges due to their scarcity and radiological hazards. Consequently, chemical secrets ranging from the accessibility of 5f/6d valence orbitals to engage in bonding, the role of spin–orbit coupling in electronic struct...

Controlling structure and reactivity by manipulating the outer-coordination sphere around a given reagent represents a longstanding challenge in chemistry. Despite advances toward solving this problem, it remains difficult to experimentally interrogate and characterize outer-coordination sphere impact. This work describes an alternative approach th...

The complex polar oxide heterojunction of SrTiO3/LaAlO3 (STO/LAO) is of great interest due to the emergent physical phenomena observed at the interface. STO and LAO separately are wide band-gap insulators. However, upon joining them at the 001, 110, and 111 crystallographic planes, the interface undergoes a transition to a conductive state. Althoug...

In this paper, we have proposed a first principle methodology to screen the transition metal complexes against a particular organic solvent and the organic solvents against a particular transition metal complex based on their solubility information without the knowledge of heat of fusion and melting temperature. The energy density of a non-aqueous...

There is significant interest in ligands that can stabilize actinide ions in oxidation states that can be exploited to chemically differentiate 5f and 4f elements. Applications range from developing large-scale...

Machine learning (ML) plays a growing role in the design and discovery of chemicals, aiming to reduce the need to perform expensive experiments and simulations. ML for such applications is promising but difficult, as models must generalize to vast chemical spaces from small training sets and must have reliable uncertainty quantification metrics to...

The Hyperspectral X-ray Imaging (HXI) project will enable non-destructive chemical-state determination of nano-scale samples in the electron microscope for nuclear safeguards applications. To efficiently measure chemical state through electron-excited X-ray emission requires a combination of wide spectral bandwidth, high resolution, and high count...

Corrosion protection is vital to ensure the reliability and long-term durability of metal components. Coating surfaces with two-dimensional (2D) materials is an attractive approach due to the strength, impermeability, and chemical inertness of many materials in this family. The selection of the best 2D coating relies on a detailed understanding of...

The separation of trivalent lanthanides and actinides is challenging because of their similar sizes and charge densities. S-donating extractants have shown significant selectivity for trivalent actinides over lanthanides, with single-stage americium/lanthanide separation efficiencies for some thiol-based extractants reported at >99.999%. While such...

Differential covalency in trivalent actinide versus lanthanide bonding with soft donors can aid separations. In their Research Article (DOI: 10.1002/anie.202017186), Enrique R. Batista, Andrew J. Gaunt, Ping Yang et al. compare electronic structure and bonding with isoradial Am3+ and Nd3+ using hard O‐ and soft Se‐donor ligands. The first structura...

Unterschiedliche Kovalenzen in der Bindung dreiwertiger Actinide und Lanthanide mit weichen Donoren können Stofftrennungen unterstützen. In ihrem Forschungsartikel (DOI: 10.1002/ange.202017186) vergleichen Enrique R. Batista, Andrew J. Gaunt, Ping Yang et al. die Bindung der isoradialen Am3+‐ und Nd3+‐Ionen mit harten O‐ und weichen Se‐Donor‐Ligand...

Covalency is often considered to be an influential factor in driving An³⁺ vs. Ln³⁺ selectivity invoked by soft donor ligands. This is intensely debated, particularly the extent to which An³⁺/Ln³⁺ covalency differences prevail and manifest as the f‐block is traversed, and the effects of periodic breaks beyond Pu. Herein, two Am complexes, [Am{N(E=PP...

Invited for this month's cover is the joint redox flow battery team from Sandia and Los Alamos National Laboratories. The cover image shows the stylized components of a redox flow battery (RFB) in the foreground, with renewable sources of energy generation in the background. The Review itself is available at 10.1002/cssc.202002354.

Two Am complexes, [Am{N(E=PPh2)2}3] (1‐Am, E=Se; 2‐Am, E=O) are compared to isoradial [Nd{N(E=PPh2)2}3] (1‐Nd, 2‐Nd) complexes. Covalent contributions are assessed and compared to U/La and Pu/Ce analogues. Through ab initio calculations grounded in UV‐vis‐NIR spectroscopy and single‐crystal X‐ray structures, we observe differences in f‐orbital invo...

Non-aqueous redox flow batteries (RFBs) have been gaining increased attention in the energy storage arena. Some of their attractive features include the promise for high energy densities, wider voltage windows compared to aqueous systems, as well as wider operating temperature ranges. One of the major challenges in the development of these systems...

The Front Cover shows the stylized components of a redox flow battery (RFB) in the foreground, with renewable sources of energy generation in the background. More information can be found in the Review by T. C. Palmer et al.

Energy storage is becoming the chief barrier to the utilization of more renewable energy sources on the grid. With independent service operators aiming to acquire gigawatts in the next 10–20 years, there is a large need to develop a suite of new storage technologies. Redox flow batteries (RFB) may be part of the solution if certain key barriers are...

Copper dissolution in nitric acid is a historic reaction playing a central role in many industrial processes, particularly for metal recovery from the electronics to nuclear industries. The mechanism through which this process occurs is debated. In order to better understand this process, quantum chemical calculations were performed to elucidate th...

We present an optimized density-functional tight-binding (DFTB) parameterization for iron-based complexes based on the popular trans3d set of parameters. The transferability of the original and optimized parameterizations is assessed using a set of 50 iron complexes, which include carbonyl, cyanide, polypyridine, and cyclometalated ligands. DFTB-op...

Actinium-225 (225Ac) is an excellent candidate for targeted radiotherapeutic applications for treating cancer, because of its 10-day half-life and emission of four high-energy α2+ particles. To harness and direct the energetic potential of actinium, strongly binding chelators that remain stable in vivo during biological targeting must be developed....

Using theoretical modelling to guide our approach, substituents were selected to improve the negative and positive potentials associated with a representative metal-based redox carrier, a phenyl spaced nickel bispicolinamide complex, [Ni(bpb)], 1. To broaden the cell potential, electron donating groups were selected and installed on the pyridyl moi...

Fundamental understanding of the electronic, chemical, and structural properties of uranium oxides requires the synthesis of high crystalline quality epitaxial films of different polymorphs of one material or different phases with various oxygen valence states. We report the growth of single-phase epitaxial UO2, α-U3O8 and α-UO3 thin films using pu...

The fluorite structured actinide dioxides (AnO2), especially UO2, are the most common nuclear fuel materials. A comprehensive understanding of their surface chemistry is critical because of its relevance to the safe handling, usage, and storage of nuclear fuels. Because of the ubiquitous nature of water (H2O), its interaction with AnO2 has attracte...

We present an integrated experimental and theoretical study of the structural behavior of U3Si5 at high-pressure conditions using angle-dispersive synchrotron X-ray diffraction (XRD) in a diamond anvil cell (DAC) and density functional theory (DFT) calculations. On increasing pressure, the ambient hexagonal structure of U3Si5 with space group P6/mm...

The speciation of NO2, NO, and N2O gases formed from the dissolution of copper in nitric acid is measured and characterized using Fourier-transform infrared (FTIR) spectroscopy. This study describes analysis of the gas phase species formed and ingrowths of their concentrations as a function of time. Acid concentrations range from 14 to 4 M and the...

Bialkali photocathodes, such as cesium potassium antimonide (CsK2Sb), can generate a high-brightness electron beam using a high-power green laser. These photocathode materials have potential applications in advanced accelerators and electron microscopes. It is known that the quantum efficiency (QE) of these photocathodes is affected severely by the...

A redox pair of Ce4+ and Ce3+ complexes has been prepared that is stabilized by the [(NP(1,2-bis- t Bu-diamidoethane)(NEt2))]1- ligand. Since these complexes are isostructural to the recently reported isovalent terbium analogs, a detailed structural and spectroscopic comparative analysis was pursued via Voronoi-Dirichlet polyhedra analysis, UV-vis...

The speciation of gases formed in the vapor phase above HNO3-H2O mixtures at room temperature is measured and characterized using Fourier-transform infrared (FTIR) spectroscopy. Although studies of speciation of compounds have been performed in the solution phase, this study focuses solely on the gas phase species formed over HNO3-H2O mixtures and...

The first density functional tight-binding (DFTB) parameters for uranium, oxygen, and hydrogen chemistry are reported, which enable quantum molecular dynamics simulations that will be instrumental in understanding actinide speciation, reaction mechanisms, and kinetics. These parameters were fitted to atomization energies and forces obtained from de...

In all known examples of metal–ligand (M–L) δ and φ bonds, the metal orbitals are aligned to the ligand orbitals in a “head-to-head” or “side-to-head” fashion. Here, we report two fundamentally new types of M–L δ and φ interactions; “head-to-side” δ and “side-to-side” φ back-bonding, found in complexes of metallacyclopropenes and metallacyclocumule...

Alkali-based semiconducting photocathodes, due to their high quantum efficiency (QE) in the visible light spectrum, are promising candidates to replace traditional metal photocathodes for high-brightness beam applications such as x-ray free electron lasers (XFELs). However, they suffer from rapid degradation which significantly limits their operati...

We provide a strategy to optimize density functional tight-binding (DFTB) parameterization for the calculation of the structures and properties of organic molecules consisting of hydrogen, carbon, nitrogen, and oxygen. We utilize an objective function based on similarity measurements and the Particle Swarm Optimization (PSO) method to find an optim...

Previous magnetic, spectroscopic, and theoretical studies of cerocene, Ce(C8H8)2, have provided evidence for non-negligible 4f-electron density on Ce and implied that charge transfer from the ligands occurs as a result of covalent bonding. Strong correlations of the localized 4f-electrons to the delocalized ligand π-system result in emergence of Ko...

A major chemical challenge facing implementation of 225Ac in targeted alpha therapy-an emerging technology that has potential for treatment of disease-is identifying an 225Ac chelator that is compatible with in vivo applications. It is unclear how to tailor a chelator for Ac binding because Ac coordination chemistry is poorly defined. Most Ac chemi...

Organometallic americium synthetic chemistry has been dormant for decades. Now, E. R. Batista, W. J. Evans, A. J. Gaunt, S. A. Kozimor, P. Yang et al. report the crystallographically characterized complex [Am(C5Me4H)3], featuring the first quantitative measurement of Am−C molecular bonding interactions. In their Communication (DOI: 10.1002/anie.201...

We report the small‐scale synthesis, isolated yield, single‐crystal X‐ray structure, ¹H NMR solution spectroscopy /solid‐state UV/Vis‐nIR spectroscopy, and density functional theory (DFT)/ab initio wave function theory calculations on an Am³⁺ organometallic complex, [Am(C5Me4H)3] (1). This constitutes the first quantitative data on Am−C bonding in...

Metallorganische Americium‐Synthesechemie wurde über Jahrzehnte kaum beachtet. Nun berichten E. R. Batista, W. J. Evans, A. J. Gaunt, S. A. Kozimor, P. Yang et al. über den kristallographisch charakterisierten Komplex [Am(C5Me4H)3], inklusive der ersten quantitativen Bestimmung molekularer Am‐C‐Wechselwirkungen. In ihrer Zuschrift (DOI: 10.1002/ang...

Synthetic strategies to yield molecular complexes of high-valent lanthanides, other than the ubiquitous Ce⁴⁺ ion, are exceptionally rare, and thorough, detailed characterization in these systems is limited by complex lifetime and reaction and isolation conditions. The synthesis of high-symmetry complexes in high purity with significant l...

A predictive model based on first principles calculations has been proposed to study the solid-liquid equilibria comprising of metal complexes and ionic liquids. The model is based on first principle COSMO calculation followed by post statistical thermodynamical treatment of self-consistent properties of solute and solvent molecules. The metal comp...

Captain Americium: Die erste strukturelle Charakterisierung einer molekularen Am-C-Wechselwirkung wurde mit Standard-Charakterisierungstechniken der synthetischen Chemie, einschließlich ¹H-NMR- und UV/Vis/NIR-Spektroskopie in Lösung, durchgeführt. Theoretische Modelle der elektronischen Struktur sind in ausgezeichneter Übereinstimmung mit den exper...

The homoleptic complexes of cerium with the tris(piperidinyl)imidophosphorane ligand, [NP(pip)3]-, present the most negative Ce3+/4+ redox couple known (<-2.64 V vs Fc/Fc+). This dramatic stabilization of the cerium tetravalent oxidation state [>4.0 V shift from the Ce3+/4+ couple in 1 M HClO4(aq)] is established through reactivity studies. Spectro...

The Cover Feature shows the interaction between theory and experiment that was used to identify prospective redox carriers for a flow battery. More information can be found in the Communication by T. Chu and I. A. Popov et al.

The use of nickel complexes utilizing non‐innocent ligands based on picolinamide to function as redox carriers in flow batteries was explored. The picolinamide moiety was linked together with −CH2CH2− (bpen), −CH2CH2CH2− (bppn), and −C6H4− (bpb) moieties, resulting in two, three, and four quasi‐reversible waves, respectively, for the nickel complex...

Flow Batteries are highly popular as storage device and can store large amount of charges in stationary applications. High efficiency flow cells have become an important option to store electric energy on a grid scale. The efficiency of flow battery depends on the energy density which is directly depends on the solubility of ions in the aqueous ele...