Search NASA⌕ Search

SEARCH · Search NASA

Results for “TBA”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Probing the Framework Metal Dependent Properties of Actinide-Centered Polyoxoalkoxide Sandwich-Type Complexes

Development of a simple and scalable synthesis of (TBA) 3 [W 5 O 18 MoNO] provides for the formation of the mixed-metal lacunary polyoxoalkoxide, (TBA) 2 [W 4 O 13 (OMe) 4 MoNO][Na(MeOH)]. This complex was used to synthesize a series of polyoxoalkoxide sandwich-type complexes with the general formula (TBA) 2 [M{W 4 O 13 (OMe) 4 MoNO} 2 ], where M = Zr(IV), Hf(IV), Th(IV), U(IV), and Np(IV). Compared to the analogous all-molybdenum complexes, the series have drastically different optical and redox properties. The results indicate that framework metal substitution acts as a tool for “orbital engineering”, with Density Functional Theory (DFT) calculations revealing that the major consequence of incorporation of tungsten into the complexes is localization of LUMO and LUMO+1 on the molybdenum centers remaining in the molecule. The change in the distribution of the frontier orbitals translates to discrepancies in the electronic properties of the series. Given the rarity of polyoxometalate complexes featuring a U(V) ion, one electron oxidation of (TBA) 2 [U(IV){W 4 O 13 (OMe) 4 MoNO} 2 ] was pursued. Isolation of the corresponding U(V) centered sandwich-type complex is reported, only the second example of U(V)-polyoxometalate complex described to date.

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

Isolation of Ce( IV ) centered polyoxoalkoxide sandwich-type complexes allows comparison of metal–oxygen bond covalency

The new Ce III centered sandwich-type complex (TBA) 3 [Ce{W 4 O 13 (OMe) 4 MoNO} 2 ] is reported. The redox properties of this molecule, and its all-molybdenum analogue, (TBA) 3 [Ce{Mo 5 O 13 (OMe) 4 NO} 2 ], were investigated using cyclic voltammetry. The data reveals the presence of reversible Ce IV /Ce III redox couples at modest potentials. One electron oxidation of the complexes provides facile access to the corresponding Ce IV derivatives, which were fully characterized. 17 O NMR spectroscopy reveals that the chemical shifts of the oxygen nuclei directly bound to Ce IV are much higher than the corresponding signals in isostructural, diamagnetic, Zr IV , Hf IV , or Th IV centered complexes. Density functional theory (DFT) calculations indicate that the increase in chemical shift correlates with an increase in the covalency of the M IV –O bonds, illustrating that 17 O NMR spectroscopy is a powerful experimental tool for interrogating the nature of metal oxygen bonding in diamagnetic complexes.

Shiels, Dominic [Univ. of Rochester, NY (United St↗
DOE OSTI2026

Emergent ferromagnetism and unusual irreversible magnetoresistance in an intercalated van der Waals antiferromagnet

Orthorhombic air-stable two-dimensional (2D) antiferromagnet (AFM) CrSBr has attracted much research interest lately thanks to its rich magnetic behaviors together with its remarkable electronic, excitonic, and polaritonic properties. Here, we report a reliable electrochemical intercalation method by inserting large tetrabutylammonium (TBA + ) ions into CrSBr layers. Magnetically, such intercalation efficiently suppresses the interlayer AFM and induces a ferromagnetic (FM) order with a much-enhanced transition temperature up to 200 K, nearly 70 K higher than the AFM onset of 132 K in pristine CrSBr. Electronically, the TBA + intercalation not only increases the electric conductivity of CrSBr, which is further enhanced by magnetic fields, but also introduces a giant negative irreversible magnetoresistance. This work demonstrates the tunable magnetic and electronic properties of CrSBr as well as their interplay, paving the way for advanced spintronic and magnetic memory devices.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Multi-Beam-Energy Control Unit Based on Triple-Bend Achromats

X-ray free electron lasers (XFELs) are the new generation of particle accelerator-based light sources, capable of producing tunable, high-power X-ray pulses that are increasingly vital across various scientific disciplines. Recently, continuous-wave (CW) XFELs driven by superconducting linear accelerators have garnered significant attention due to their ability to enhance availability by supporting multiple undulator lines simultaneously. In this paper, we introduce a novel delay system comprising four triple-bend achromats (TBAs). This delay system was combined with fast kickers and can be employed to generate electron beams on a bunch-to-bunch basis in a CW-XFEL facility. Based on the parameters of the Shanghai High-Repetition-Rate XFEL and Extreme Light Facility, start-to-end simulations demonstrate that the TBA-based delay system achieves excellent electron beam qualities while providing a wide beam-energy-tuning range from 1.39 to 8 GeV.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Thorium Bis‐Salophen Trimers as Anion Detectors and Binding Agents

Bis‐salophen ligands are the condensation product of a tetramine and a salicylaldehyde derivative. They feature two binding sites, both of which are tetradentate with mixed O/N donor atoms. Reaction with the ligand precursor and thorium nitrate tetrahydrate forms a 3:3 metal‐to‐ligand trimer with a ΔΔΔ‐chirality confirmed by X‐ray crystallography of a racemic single crystal. The structure has a pore in the center of the triangular structure measuring 6.22 Å at its narrowest point. This compound is air‐ and water‐stable as well as soluble in organic solvents. Here, this compound was screened with a series of tetrabutyl ammonium halide salts, and tetrabutylammonium (TBA) chloride showed the strongest binding to the complex. After the addition of 2 equivalents of TBACl, the complex and salt precipitate out of solution.

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

Coordination Chemistry and Photoluminescence of Sm(II) Dibenzo-24-crown-8 Complexes

Three Sm(II) dibenzo-24-crown-8 (db24c8) complexes were synthesized in anhydrous, air-free conditions via the reaction of SmI 2 with db24c8 and tetrabutylammonium tetraphenylborate ([TBA][BPh 4 ]; where needed) in acetonitrile (CH 3 CN), dimethoxyethane (DME), and tetrahydrofuran (THF) to yield [Sm(db24c8)(CH 3 CN) 2 ][BPh 4 ][I]·CH 3 CN, [Sm(db24c8)(DME)]I 2 , and [Sm(db24c8)(THF) 2 ]I 2 , respectively. In each case, a 10-coordinate, staggered dodecahedral (2:6:2) environment is formed around the Sm 2+ center that is completed by either two solvent molecules (CH 3 CN or THF) or one bidentate solvent molecule (DME). Inner-sphere solvent molecules can be excluded by reacting SmI 2 with db24c8 in 1:3 THF:toluene to yield Sm(db24c8)I 2 . Here, this molecule features a distorted, eight-coordinate, hexagonal pyramidal Sm 2+ metal center, where the coordinated db24c8 molecule shows a torsion angle unexpectedly close to the 180° antiperiplanar arrangement and two uncoordinated db24c8 oxygen atoms. Solution UV–vis–NIR measurements demonstrate that Sm 2+ is a good size match for the cavity of various db24c8 conformations and that Eu 2+ and Yb 2+ exhibit competition between acetonitrile solvation and the Eu 2+ and Yb 2+ /db24c8 complexes in solution. During excitation by 546 nm light, both [Sm(db24c8)(DME)]I 2 and [Sm(db24c8)(THF) 2 ]I 2 exhibit mixed 5d → 4f and 4f → 4f emission at 20 °C and exclusively 4f → 4f at −180 °C, whereas Sm(db24c8)I 2 only shows 5d → 4f emission regardless of temperature. Photoluminescence from [Sm(db24c8)(CH 3 CN) 2 ][BPh 4 ][I]·CH 3 CN is quenched.

Cations↗
DOE OSTI2025

Quantitative and mechanistic insights into proton dynamics for fast energy storage

Proton conduction in hydrogen-bond-rich protic electrolytes enables fast mass and charge transport, crucial for electrochemical energy storage and power conversion. Such transport can give proton-based batteries exceptional rate capability and low-temperature operation beyond other working ions. Here we show that in phosphoric acid (H 3 PO 4 ) electrolytes, vehicular and structural proton transport coexist, and their contributions to conductivity can be quantitatively distinguished. We link structural diffusion directly to hydrogen-bond strength, enabling the precise tuning of proton migration. Guided by this, we reveal a double conductivity peak from regulated structural diffusion. The optimal electrolyte (5.8-M H 3 PO 4 ) achieves high overall (232.9 mS cm −1 ) and structural (164.9 mS cm−1) conductivity. A MoO 3 ‖CuFe-TBA battery with this electrolyte outperforms a deep-eutectic benchmark (8.3-M H 3 PO 4 ), delivering >17,474 W kg −1 at room temperature and retaining 15.1 Wh kg −1 at −75 °C. These findings provide a framework for designing advanced protic electrolytes across electrochemical systems.

Li, Ziyue [Fudan University, Shanghai (China, Peop↗