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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Radiation Effects in Next Generation Used Nuclear Fuel Reprocessing Strategies

With the global community committed to significantly expanding nuclear energy capacity, the development of efficient used nuclear fuel (UNF) management strategies has become more critical than ever. These strategies are vital to fostering the widespread adoption of closed fuel cycles, which are essential for sustainable nuclear energy production and security. Achieving this ambitious goal necessitates a comprehensive understanding of radiation effects on next-generation technologies, as radiolysis can often limit the longevity and performance of these systems. This seminar will provide an overview of next-generation UNF reprocessing strategies, highlighting the latest advancements and innovative approaches in the field. Particular attention will be given to two key areas of recent research: 1. Radiation robustness and performance of advanced sulfur chloride-based chlorination technologies. We will explore the efficacy of sulfur chloride-based chlorination processes in the presence of surrogate cladding materials, specifically aluminum. These processes have shown promise in the dissolution, decontamination, and recovery of cladding materials for reuse. Detailed findings on how the composition and performance of these sulfur chloride solvents respond to radiation exposure will be discussed. 2. Impacts of metal ion complexation and direct dissolution conditions on monoamide-based reprocessing strategies. We will delve into the time-resolved and dose accumulation effects of irradiation on the direct dissolution of voloxidized uranium and rhenium using N,N-di-(2-ethylhexyl) butyramide (DEHBA) or N,N-di-(2-ethylhexyl)isobutyramide (DEHiBA) in pre-equilibrated n-dodecane solvent. The implications of these interactions on dissolution efficiency, radiolytic stability, and overall process performance will be examined. These studies aim to underscore the importance of understanding radiation effects in the development of next-generation UNF reprocessing technologies and the global transition towards more sustainable and efficient nuclear energy systems.

38 - RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCL↗
DOE OSTI2023

Comparing π‐complexation capabilities of ionic liquids containing silver(I) and copper(I) ions by headspace single drop microextraction in combination with high‐performance liquid chromatography

Selective π‐complexation capabilities of silver(I) and copper(I) ions can be effectively facilitated in ionic liquids. To understand the effects of environmental factors that influence the π‐complexation of these metal ions with analytes, techniques that employ small volumes of ionic liquid that can be readily analyzed are desired. In this study, headspace single drop microextraction coupled with HPLC is used to investigate a diverse set of environmental factors on the metal ion‐mediated complexation with aromatic compounds in ionic liquid media. Silver(I) and copper(I) bis[(trifluoromethyl)sulfonyl]imide salts were both studied by dissolving them in the 1‐decyl‐3‐methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ionic liquid and employing the mixture as extraction media for aromatic compounds. Water and acetonitrile within the sample solution were observed to interfere with the complexation of silver(I) ions and aromatic compounds, while ethylene glycol and triethylene glycol did not. The temperature and extraction times were optimized to fully facilitate the π‐complexation capabilities of metal ions in ionic liquid media. Partition coefficients between the sample headspace and metal ion were determined using a three‐phase equilibria model. Although no discernable difference in analyte partitioning between the headspace and ionic liquid solvent was observed, analyte partition coefficients to silver(I) ion tended to be greater compared to copper(I) ion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

The impact of the electric field of metal ions on the vibrations and internal hydrogen bond strength in alkali metal ion di- and triglycine complexes

Using infrared predissociation spectroscopy of cryogenic ions, we revisit the vibrational spectra of alkali metal ion (Li+, Na+, K+) di- and triglycine complexes. We assign their most stable conformation, which involves metal ion coordination to all C=O groups and an internal NH⋯NH2 hydrogen bond in the peptide backbone. An analysis of the spectral shifts of the OH and C=O stretching vibrations across the different metal ions and peptide chain lengths shows that these are largely caused by the electric field of the metal ion, which varies in strength as a function of the square of the distance. The metal ion–peptide interaction also remotely modulates the strength of internal hydrogen bonding in the peptide backbone via the weakening of the amide C=O bond, resulting in a decrease in internal hydrogen bond strength from Li+ > Na+ > K+.

Chemistry↗
DOE OSTI2023

Influence of Rare-Earth Ion Radius on Metal–Metal Charge Transfer in Trinuclear Mixed-Valent Complexes

We report the synthesis and characterization of a highly conjugated bisferrocenyl pyrrolediimine ligand, Fc 2 PyrDIH (1), and its trinuclear complexes with rare earth ions—(Fc 2 PyrDI)M(N(TMS) 2 ) 2 (2-M, M = Sc, Y, Lu, La). Crystal structures, NMR spectra, and UV/Vis-NIR data are presented. The latter are in good agreement with DFT calculations, illuminating the impact of the rare earth ionic radius on NIR charge transfer excitations. For [2-Sc] + , the charge transfer is at 11500 cm -1 , while for [2-Y] + only a d-d transition at 8000 cm -1 is observed. Lu has an ionic radius in between Sc and Y, and the [2-Lu] + complex exhibits both transitions. From TDDFT analysis we assign the 11500 cm -1 transition as a mixture of MLCT and MMCT, rather than pure metal-to-metal CT, because it has significant ligand character. Typically, the ferrocenes have high rotational freedom in bis-ferrocenyl mixed valent complexes. However, in the present (Fc 2 PyrDI)M(N(TMS) 2 ) 2 complexes, ligand-ligand repulsions lock the rotational freedom, so that rare earth ionic radius-dependent geometric differences increasingly influence orbital overlap as the ionic radius falls. The Marcus-Hush coupling constant HAB trends as: [2-Sc] + >[2-Lu] + >[2-Y] +

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Cryogenic and Temperature-Dependent Photoelectron Spectroscopy of Metal Complexes

Negative ion photoelectron spectroscopy (NIPES) coupled with electrospray ionization (ESI) has been proved to be a powerful gas-phase spectroscopic tool for characterizing electronic structures and chemical bonding of a variety of cluster anions and corresponding neutral radicals involved in the condensed phase reactions and transformations. Since the acquisition of cryogenic and temperature-controlling capabilities, broader range of research scope has been covered. This review summarizes our recent investigations on metal complexes employing cryogenic ESI-NIPES that provide us essential information towards understanding complicated condensed phase reactions including hydrocarbon activations and electron transfer reactions, and afford us spectroscopic probe of highly reactive transient species and intimate redox pairs. Special attention has been drawn to connect gas phase photodetachment processes with solution phase redox reactions. Photodetachment of transition metal-EDTA complexes has been systematically investigated to model the sequential oxidation reactions of these species in solutions. The obtained gas phase electron affinity (EA) is compared with the solution redox potential (E1/2) and the metal ionization potential (IP) for several series of homologous metal complexes to emphasize their intrinsic correlations with deviations being largely modulated by different degrees of ligand participations.

Yuan, Qinqin↗
DOE OSTI2023

Influence of aluminum incorporation and aqueous conditions on metal ion release of high-Ni transition metal oxide nanomaterials

Developing a materials perspective of how to control the degradation and negative impact of complex metal oxides requires an integrated understanding of how these nanomaterials transform in the environment and interact with biological systems. Doping with aluminum is known to stabilize oxide materials, but has not been assessed cohesively from synthesis to environmental fate and biological impact. In the present study, the influence of aluminum doping on metal ion release from transition metal oxides was investigated by comparing aqueous transformations of lithium nickel cobalt aluminum oxide (LiNi 0.82 Co 0.15 Al 0.03 O 2 ; NCA) and lithium nickel cobalt oxide (LiNi 0.80 Co 0.20 O 2 ; NC) nanoparticles and by calculating the energetics of metal release using a density functional theory (DFT) and thermodynamics method. Two model environmental organisms were used to assess biological impact, and metal ion release was compared for NCA and NC nanoparticles incubated in their respective growth media: moderately hard reconstituted water (MHRW) for the freshwater invertebrate Daphnia magna (D. magna) and minimal growth medium for the Gram-negative bacterium Shewanella oneidensis MR-1 (S. oneidensis). Further, the amount of metal ions released was reduced for NCA compared to NC in MHRW, which correlated to changes in the modeled energetics of release upon Al substitution in the lattice. In minimal medium, metal ion release was approximately an order of magnitude higher compared to MHRW and was similar to the stoichiometry of the bulk nanoparticles for both NCA and NC. Interpretation of the release profiles and modeling indicated that the increase in total metal ion release and the reduced influence of Al doping arises from lactate complexation of metal ions in solution. The relative biological impacts of NC and NCA exposure for both S. oneidensis and D. magna were consistent with the metal release trends observed for minimal medium and MHRW, respectively. Together, these results demonstrate how a combined experimental and computational approach provides valuable insight into the aqueous transformations and biological impacts of complex metal oxide nanoparticles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Extraction, Characterization, and Stability Studies of Bistriazinyl-Derived Carboxylic Acids

Separation of An(III) and Ln(III) ions will benefit the recycling of used nuclear fuel (UNF). For this purpose, many ligands have been tested over the years, and several separation processes have been successfully demonstrated on the laboratory scale. Current research aims at the development of new ligands that are built only with carbon, hydrogen, oxygen, and nitrogen (CHON), as they can be incinerated completely without secondary waste production. Here, we tested a new class of water-soluble ligands, the bistriazinyl-octa-carboxylic acids. One member, in particular, 2,6-bis-[5,6-di(3,4-dicarboxyphenyl)-1,2,4- triazin-3-yl]-pyridine (BTPOA), was found to be suitable for the selective separation of Am(III) and Cm(III) ions from Ln(III) ions and may act as a CHON alternative to its sulfonated analogue (SO 3 -Ph-BTP). BTPOA exhibited good extraction results and a high selectivity for Am(III) over Eu(III) ions. This ligand’s complexation of metal ions was further studied using potentiometric spectroscopy, as well as time-resolved laser-induced spectroscopy with Cm(III) and Eu(III) in aqueous HClO 4 and HNO 3 media. Conditional stability constants of each formed species were determined. In the HClO 4 system, Cm(III) formed three species (1:1, 1:2, and 1:3) through the stepwise addition of a single BTPOA molecule. On the other hand, in HNO 3 , Cm(III) formed two 1:2 complexes and one 1:3 complex, while the stepwise formation of three species was observed for Eu(III). The stability constants are comparable to the values for SO 3 -Ph-BTP. The radiolytic behavior of BTPOA was also investigated using electron pulse irradiation measurements to determine absolute rate coefficients (k) under ambient temperature conditions for the reaction of BTPOA with typical UNF reprocessing radical radiolysis products the hydrated electron (e aq − , k = (1.60 ± 0.02) × 10 10 M −1 s −1 ), the hydrogen atom (H • , k = (2.17 ± 0.03) × 10 9 M −1 s −1 ), and hydroxyl ( • OH, k = (6.95 ± 0.06) × 10 9 M −1 s −1 ) and nitrate (NO 3 • , k = (0.37 ± 0.02) × 10 7 M −1 s−1) radicals. These rate coefficients indicate that the radiolytic longevity of BTPOA should increase with HNO 3 concentration, owing to the consumption of e aq − /H • , by nitrate anions, and the replacement of • OH by the less reactive NO 3 • .

Diaz Gomez, Laura [Forschungszentrum Juelich (Germ↗
DOE OSTI2022

Vibrational signatures of HNO 3 acidity when complexed with microhydrated alkali metal ions, M + ∙(HNO 3 )(H 2 O) n =5 (M = Li, K, Na, Rb, Cs), at 20 K

The speciation of strong acids like HNO 3 under conditions of restricted hydration is an important factor in the rates of chemical reactions at the air-water interface. Here we explore the trade-offs in play when HNO 3 is attached to alkali ions (Li + -Cs + ) with four water molecules in their primary hydration shells. This is achieved by analyzing the vibrational spectra of the M + ∙(HNO 3 )(H 2 O) 5 clusters cooled to about 20 K in a cryogenic photofragmentation mass spectrometer. The local acidity of the acidic OH group is estimated by the extent of the red shift in its stretching frequency when attached to a single water molecule. Here, the persistence of this local structural motif (HNO 3 -H 2 O) in all of these alkali metal clusters enables us to determine the competition between the effect of the direct complexation of the acid with the cation, which acts to enhance acidity, and the role of the water network in the first hydration shell around the ions, which acts to counter (screen) the intrinsic effect of the ion. Analysis of the vibrational features associated with the acid molecule as well as those of the water network reveal how cooperative interactions in the micro hydration regime conspire to effectively offset the intrinsic enhancement of HNO 3 acidity afforded by attachment to the smaller cations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Alkali Metal Ions Dictate the Structure and Reactivity of an Iron(II) Imido Complex

The presence of redox innocent metal ions has been proposed to modulate the reactivity of metal ligand multiple bonds; however, insight from structure/function relationships is limited. Here, alkali metal reduction of the Fe(III) imido complex [Ph 2 B( t BuIm) 2 Fe=NDipp] (1) provides the series of structurally characterized Fe(II) imido complexes [Ph 2 B( t BuIm) 2 Fe=NDippLi(THF) 2 ] (2), [Ph 2 B( t BuIm) 2 Fe=NDippNa(THF) 3 ] (3), and [Ph 2 B( t BuIm) 2 Fe=NDippK] 2 (4), in which the alkali metal cations coordinate the imido ligand. Structural investigations demonstrate that the alkali metal ions modestly lengthen the Fe=N bond distance from that in the charge separated complex [Ph 2 B( t BuIm) 2 Fe=NDipp][K(18-C-6)THF 2 ] (5), with the longest bond observed for the smallest alkali metal ion. In contrast to 5, the imido ligands in 2–4 can be protonated and alkylated to afford Fe(II) amido complexes. Combined experimental and computational studies reveal that the alkali metal polarizes the Fe=N bond, and the basicity of imido ligand increases according to 5 < 4 ≈ 3 < 2. The basicity of the imido ligands influences the relative rates of reaction with 1,4-cyclohexadiene, specifically by gating access to complex 5, which is the species that is active for HAT. All complexes 2–4 react with benzophenone form metastable Fe(II) intermediates that subsequently eliminate the metathesis product Ph 2 C=NDipp, with relative rates dependent on the alkali metal ion. By contrast, the same reaction with 5 does not lead to the formation of Ph 2 C=NDipp. Furthermore, these results demonstrate that the coordination of alkali metal ions dictate both the structure and reactivity of the imido ligand and moreover can direct the reactivity of reaction intermediates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Structural and Spectroscopic Characterization of Plutonium and Other Tetravalent Metals Complexed to a Keggin Ion

Here, we report the isolation of the first plutonium(IV) complex with a Keggin ion chelator: Cs 20 [Pu(PW 11 O 39 ) 2 ] 2 ·13H 2 O. Single crystal XRD and solid-state UV–vis absorbance analysis demonstrate the stabilization of Pu 4+ by the Keggin ligand. The unit cell contains two [Pu(PW 11 O 39 ) 2 ] 10– complexes (Pu(PW 11 ) 2 ) bridged by Cs + . Raman and 31 P NMR spectra of Pu(PW 11 ) 2 are consistent with the analogous Zr 4+ , Hf 4+ , Ce 4+ , and Th 4+ complexes. The Pu–O bond distances at the two Pu sites are 2.35(3) and 2.34(3) Å, matching the value extrapolated from the bonding trend built with the other 8-coordinated tetravalent cations. However, the long-range arrangement of the Pu(PW 11 ) 2 complexes within the lattice is unique in the series of M IV (PW 11 ) 2 compounds: pairs of Pu(PW 11 ) 2 are organized perpendicular to each other. Based on solution-state UV–visible absorbance, small-angle X-ray scattering (SAXS), and 31 P NMR, the tetravalent cations quantitatively form the 1:2 species in solution ([Pu(PW 11 O 39 ) 2 ] 10– (aq) ) and no 1:1 species ([Pu(PW 11 O 39 )(H 2 O) x ] 3– (aq) ). Finally, a linear correlation exists between the metal–oxygen distances in the M IV (PW 11 ) 2 compounds and the corresponding metal dioxides, allowing for extrapolation for Pa 4+ , Am 4+ , and Bk 4+ . The results indicate that our microscale POM approach represents a viable pathway to probe properties of rare actinide ions in discrete molecules, beyond the traditional oxide extended solids.

and nuclear chemistry↗
DOE OSTI2020

Aqueous electrocatalytic CO 2 reduction using metal complexes dispersed in polymer ion gels

We use fac-[Re(bpy)(CO) 3 Cl] ([Re–Cl]) dispersed in polymer ion gel (PIG) ([Re]–PIG) to carry out electrocatalytic CO 2 reduction in water. Electrolysis at -0.68 V vs. RHE in a CO 2 -saturated KOH and K 2 CO 3 solution produces CO with over 90% Faradaic efficiency. The PIG electrode is readily combined with water oxidation catalysts to generate a full electrochemical cell. Additionally, we provide evidence that the PIG electrode can be implemented with other molecular catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Effects on Human Non-Small Lung Cancer Cell growth of Cu(II), Au(III) and Re(I) Complexes Containing N-donor Pyridyl Ligands: A Senior Undergraduate Research Project

Hands-on synthetic laboratory experiences are critically important for undergraduate chemistry majors. A senior undergraduate research experience at the College of Wooster is presented in the current work. The inorganic complexes [Cu(phenan) 2 (NO 3 ) 2 ] (1; phenan = phenanthridine) and [Au(phenan)Cl 3 ](2) were prepared by metallation of the phenan ligand in a 1:1 CH 3 OH/CH 2 Cl 2 mixture at room temperature. Complex 1 is a new inorganic coordination compound. The structures were confirmed by X-ray crystallography. Complex 1 reveals a distorted octahedral geometry around the central Cu (II) metal ion. In complex 2, the Au(III) atom exhibits a square planar geometry. In addition, we investigated [Cu(dmeobpy)(H 2 O) 2 ][NO 3 ] 2 (3; dmeobpy = 4,4’-dimethoxy-2,2’-bipyridine), [Cu(bap)(NO 3 ) 2 ](4; bap = 2,6-bis(azaindole)pyridine) and [Re(CO) 3 (dmeobpy)Cl] (5). The cytoxocities of 1-5, phenan, dmeobpy, bap and cisplatin were evaluated against several human non-small cell lung cancer cell lines (NCI-H1975, HCC827, NCI-H460, and NCI-A549). Compound 1 exhibited modest antitumor activity against the HCC827 cell line, with an IC 50 value of 19 µM. Compound 3 exhibits lower cytotoxic activity than 1. Finally, the cytotoxic activity of complex 5 (IC 50 < 11 µM) is significantly greater than 1 and 3 against the H1975 cancer cell line.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Ion-specific clustering of metal-amphiphile complexes in rare earth separations

The nanoscale structure of a complex fluid can play a major role in the selective adsorption of ions at the nanometric interfaces, which is crucial in industrial and technological applications. Here we study the effect of anions and lanthanide ions on the nanoscale structure of a complex fluid formed by metal-amphiphile complexes, using small angle X-ray scattering. The nano- and mesoscale structures we observed can be directly connected to the preferential transfer of light (La and Nd) or heavy (Er and Lu) lanthanides into the complex fluid from an aqueous solution. While toluene-based complex fluids containing trioctylmethylammonium-nitrate (TOMA-nitrate) always show the same mesoscale hierarchical structure regardless of lanthanide loading and prefer light lanthanides, those containing TOMA-thiocyanate show an evolution of the mesoscale structure as a function of the lanthanide loading and prefer heavy lanthanides. The hierarchical structure indicates the presence of attractive interactions between ion-amphiphile aggregates, causing them to form clusters. A clustering model that accounts for the hard sphere repulsions and short-range attractions between the aggregates has been adapted to model the X-ray scattering results. The new model successfully describes the nanoscale structure and helps in understanding the mechanisms responsible for amphiphile assisted ion transport between immiscible liquids. Accordingly, our results imply different mechanisms of lanthanide transport depending on the anion present in the complex fluid and correspond with anion-dependent trends in rare earth separations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

In situ mechanical reinforcement of polymer hydrogels via metal-coordinated crosslink mineralization

Biological organic-inorganic materials remain a popular source of inspiration for bioinspired materials design and engineering. Inspired by the self-assembling metal-reinforced mussel holdfast threads, we tested if metal-coordinate polymer networks can be utilized as simple composite scaffolds for direct in situ crosslink mineralization. Starting with aqueous solutions of polymers end-functionalized with metal-coordinating ligands of catechol or histidine, here we show that inter-molecular metal-ion coordination complexes can serve as mineral nucleation sites, whereby significant mechanical reinforcement is achieved upon nanoscale particle growth directly at the metal-coordinate network crosslink sites.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Project 18-15263 X-ray Studies of Interfacial Molecular Complexes in ALSEP Back-Extraction (Research Performance Final Report)

The objective of the project was to use synchrotron X-rays to measure the molecular-scale organization of extractants, complexants, buffers, and metal ions at the organic-aqueous (liquid-liquid) interface during solvent back-extraction under conditions relevant to ALSEP (Actinide-Lanthanide Separation Process). The capability of X-ray fluorescence near total reflection (XFNTR) was extended to explore the distribution of Eu(III) between the liquid-liquid interface and bulk organic and aqueous phases which contained extractants HDEHP (bis(2-ethylhexyl) phosphoric acid) and HEHEHP (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester), the complexant DTPA (diethylene triamine pentaacetic acid), and citric and nitric acids. Although an Am-compatible sample cell was developed, extending x-ray measurements of flat liquid-liquid interfaces to the actinide Am(III) did not prove to be possible within constraints imposed by the Advanced Photon Source. However, preliminary measurements with a drop cell may eventually provide a path forward to investigate Am(III) at a liquid interface. It was also demonstrated that competitive binding that occurs during back-extraction of lanthanide ions to either a phosphoric acid extractant (DHDP, di-hexadecyl phosphate) at the liquid interface or to complexant DTPA in the bulk aqueous phase could be reversibly tuned by X-ray exposure. Separately, X-ray measurements from the liquid-vapor interface explored the role of the aqueous solubility of HDEHP and HEHEHP and their interactions with a range of lanthanides and transition metal ions. Finally, the capability of X-ray absorption spectroscopy (EXAFS) was extended to probe metal ion coordination in lanthanide ion-extractant complexes at the liquid-vapor interface. Complementary to the specific interfacial systems studied during this project, the development of x-ray techniques expands our ability to understand ion ordering at liquid interfaces.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗