Photoinduced Isomerization of [N] in a Bimetallic Lutetium Complex.

The first lanthanide dinitrogen photoswitch [(CMeH)(THF)Lu](μ-η:η-N), , is reported. is a unique example of controlled isomerization between side-on and end-on coordination modes of [N] in a bimetallic lutetium dinitrogen complex that results in photochromism. Near-infrared light (NIR) was used to promote this effect, as evidenced by single X-ray diffraction (XRD) connectivity and Raman data, generating the [N] end-on bound isomer, [(CMeH)(THF)Lu](μ-η:η-N), .

Efficient Parameterization of Density Functional Tight-Binding for 5-Elements: A Th-O Case Study.

Density functional tight binding (DFTB) models for -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 orbitals is crucial to generating a reliable parametrization for -block elements, because they play import roles in bonding interactions. However, since the number of parameters grows quadratically with the number of orbitals, the computational cost for parameter optimization is much more expensive for the -elements than for the main group elements.

Unveiling Hidden Shake-Up Features in the Uranyl M-Edge Spectrum.

The M-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 effects and electron correlation. In this work, we utilize variational relativistic multireference configurational interaction methods to compute and analyze the X-ray M-edge absorption spectrum of uranyl.

Acceleration of Solvation Free Energy Calculation via Thermodynamic Integration Coupled with Gaussian Process Regression and Improved Gelman-Rubin Convergence Diagnostics.

The determination of the solvation free energy of ions and molecules holds profound importance across a spectrum of applications spanning chemistry, biology, energy storage, and the environment. Molecular dynamics simulations are powerful tools for computing this critical parameter. Nevertheless, the accurate and efficient calculation of the solvation free energy becomes a formidable endeavor when dealing with complex systems characterized by potent Coulombic interactions and sluggish ion dynamics and, consequently, slow transition across various metastable states.

Insights into the Mechanism of Neptunium Oxidation to the Heptavalent State.

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)O(OH)] during ozonolysis of aqueous MOH (M=Li, Na, K) solutions using a combined experimental and theoretical approach. All experimental reactions were closely monitored via absorption and vibrational spectroscopy to follow both the oxidation state and the speciation of neptunium guided by the calculated vibrational frequencies for various neptunium species.

Advances in heavy alkaline earth chemistry provide insight into complexation of weakly polarizing Ra, Ba, and Sr cations.

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

Impact of Surface Oxidation on the Morphology of Uranium Dioxide Nanoparticles.

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-principles calculations of the surface energies of different crystallographic planes (001, 110, and 111) as a function of the relative oxygen chemical potential and under the influence of different ligands.

Unusual Actinyl Complexes with a Redox-Active N,S-Donor Ligand.

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 different oxidation states across the actinide series.

Structure and Dynamics of NaCl/KCl/CaCl-EuCl ( = 2, 3) Molten Salts.

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 solute cations and anions and long-range solute and solvent cations are still unclear. In order to study the structural change of solute cations caused by different solvent salts, we performed first-principles molecular dynamics simulations in molten salts and extended X-ray absorption fine structure (EXAFS) measurements for the cooled molten salt samples to identify the local coordination environment of Eu and Eu ions in CaCl, NaCl, and KCl.

Architector for high-throughput cross-periodic table 3D complex building.

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-, d-, and f-block mononuclear organometallic complexes capable of capturing nearly the full diversity of the known experimental chemical space.

SARS-CoV-2 intra-host diversity, antibody response, and disease severity after reinfection by the variant of concern Gamma in Brazil.

The rapid spread of the SARS-CoV-2 Variant of Concern (VOC) Gamma in Amazonas during early 2021 fueled a second large COVID-19 epidemic wave and raised concern about the potential role of reinfections. Very few cases of reinfection associated with the VOC Gamma have been reported to date, and their potential impact on clinical, immunological, and virological parameters remains largely unexplored. Here we describe 25 cases of SARS-CoV-2 reinfection in Brazil.

Influencing Bonding Interactions of the Neptunyl (V, VI) Cations with Electron-Donating and -Withdrawing Groups.

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 for separations requires understanding how to properly tune a system toward a desired trait through functionalization.

State Interaction Linear Response Time-Dependent Density Functional Theory with Perturbative Spin-Orbit Coupling: Benchmark and Perspectives.

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 only the coupling between the ground and excited states, but also between excited states with all couplings between spin microstates.

Sulfate supply decreases barium availability, uptake, and toxicity in lettuce plants grown in a tropical Ba-contaminated soil.

Barium (Ba) is a non-essential element that can cause toxicity in living organisms and environmental contamination. Plants absorb barium predominantly in its divalent cationic form Ba. Sulfur (S) can decrease the availability of Ba in the soil by causing its precipitation as barium sulfate, a compound known for its very low solubility.

N-to-NH conversion by excess electrons trapped in point vacancies on 5-element dioxide surfaces.

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

Potentially toxic elements in iron mine tailings: Effects of reducing soil pH on available concentrations of toxic elements.

Tailings from iron mining are characterized by high concentrations of iron and manganese oxides, as well as high pH values. With these characteristics, most of the potentially toxic elements (PTE) contained in the tailings are somewhat unavailable. The aim of the present study was to evaluate how a reduction in the pH of iron mine tailings may affect PTE availabilities.

Advancing the Am Extractant Design through the Interplay among Planarity, Preorganization, and Substitution Effects.

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, Am production for industrial usage, and environmental cleanup efforts. Herein, we study a series of extractants, using first-principle calculations, to identify the electronic properties that preferentially influence Am(III) binding in separations.

Hydrazine Energy Storage: Displacing N H from the Metal Coordination Sphere.

Hydrogen carriers, such as hydrazine (N H ), may facilitate long duration energy storage, a vital component for resilient grids by enabling more renewable energy generation. Lanthanide coordination chemistry with N H as well as efforts to displace N H from the metal coordination sphere to develop an efficient catalytic production cycle were detailed. Modeling the equilibrium of different ligand coordination, it was predicted that strong sigma donor molecules would be required to displace N H .

Spectroscopic and electrochemical characterization of a Pr imidophosphorane complex and the redox chemistry of Nd and Dy complexes.

The molecular tetravalent oxidation state for praseodymium is observed in solution oxidation of the anionic trivalent precursor [K][Pr(NP(1,2-bis-Bu-diamidoethane)(NEt))] (1-Pr(NP*)) with AgI at -35 °C. The Pr complex is characterized in solution cyclic voltammetry, UV-vis-NIR electronic absorption spectroscopy, and EPR spectroscopy. Electrochemical analyses of [K][Ln(NP(1,2-bis-Bu-diamidoethane)(NEt))] (Ln = Nd and Dy) by cyclic voltammetry are reported and, in conjunction with theoretical modeling of electronic structure and oxidation potential, are indicative of principal ligand oxidations in contrast to the metal-centered oxidation observed for 1-Pr(NP*).

An Allyl Uranium(IV) Sandwich Complex: Are ϕ Bonding Interactions Possible?

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-2-enylsilyl)-2,6-diisopropylaniline (LH), was used as either the fully protonated, singly deprotonated, or doubly deprotonated form, thereby highlighting the stability and versatility of the silylanilide motif.

Relativistic Effects in Modeling the Ligand K-Edge X-ray Absorption Near-Edge Structure of Uranium Complexes.

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-component Hamiltonian in the X2C form with all of the electrons in the system being considered explicitly to compare and contrast with previous studies that included the relativistic effects by means of relativistic effective core potentials (RECPs).