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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 1,711 records · Page 95
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Multigram Synthesis of a Combustion‐Relevant δ‐Ketohydroperoxide through Sulfonylhydrazine Substitution

Abstract A synthesis of a δ‐ketohydroperoxide is described, addressing potential functional‐group compatibilities in these elusive species relevant to combustion and atmospheric chemistries. The hydroperoxide is installed via sulfonylhydrazine substitution, which was found to be more effective than displacement of secondary halides. As part of this protocol, it was observed that 1,2‐dimethoxyethane is an advantageous medium for the reaction, avoiding the formation of a tetrahydrofuran hydroperoxide side product. This discovery facilitated the multigram synthesis (6 steps, 41 % yield overall) and discrete characterization of the target δ‐ketohydroperoxide.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

High‐pressure Synthesis of Cobalt Polynitrides: Unveiling Intriguing Crystal Structures and Nitridation Behavior

Abstract In this study, we conduct extensive high‐pressure experiments to investigate phase stability in the cobalt‐nitrogen system. Through a combination of synthesis in a laser‐heated diamond anvil cell, first‐principles calculations, Raman spectroscopy, and single‐crystal X‐ray diffraction, we establish the stability fields of known high‐pressure phases, hexagonal NiAs‐type CoN, and marcasite‐type CoN 2 within the pressure range of 50–90 GPa. We synthesize and characterize previously unknown nitrides, Co 3 N 2 ,Pnma‐CoN and two polynitrides, CoN 3 and CoN 5 , within the pressure range of 90–120 GPa. Both polynitrides exhibit novel types of polymeric nitrogen chains and networks. CoN 3 feature branched‐type nitrogen trimers (N 3 ) and CoN 5 show π‐bonded nitrogen chain. As the nitrogen content in the cobalt nitride increases, the CoN 6 polyhedral frameworks transit from face‐sharing (in CoN) to edge‐sharing (in CoN 2 and CoN 3 ), and finally to isolated (in CoN 5 ). Our study provides insights into the intricate interplay between structure evolution, bonding arrangements, and high‐pressure synthesis in polynitrides, expanding the knowledge for the development of advanced energy materials

Chemistry↗
DOE OSTI2024

High‐Pressure Synthesis and Recovery of Single Crystals of the Metastable Manganese Carbide, MnC x

Abstract Transition metal carbides find widespread use throughout industry due to their high strength and resilience under extreme conditions. However, they remain largely limited to compounds formed from the early d‐block elements, since the mid‐to‐late transition metals do not form thermodynamically stable carbides. We report here the high‐pressure bulk synthesis of large single crystals of a novel metastable manganese carbide compound, MnC x (P6 3 /mmc), which adopts the anti‐NiAs‐type structure with significant substoichiometry at the carbon sites. We demonstrate how synthesis pressure modulates the carbon loading, with ~40 % occupancy being achieved at 9.9 GPa.

Chemistry↗
DOE OSTI2016

The engine reformer: Syngas production in an engine for compact gas‐to‐liquids synthesis

Methane (CH 4 ) reforming was carried out in an internal combustion engine (an “engine reformer”). We successfully produced syngas from the partial oxidation of natural gas in the cylinder of a diesel engine that was reconfigured to perform spark ignition. Performing the reaction in an engine cylinder allows some of the exothermicity to be captured as useful work. Intake conditions of 110 kPa and up to 480 °C allowed low cycle‐to‐cycle variability ( COV nimep < 20 %) at methane‐air equivalence ratios ( ϕ M ) of 2.0, producing syngas with an H 2 ‐to‐CO ratio of 1.4. Spark ignition timing was varied between 45–30° before top‐dead‐center (BTDC) piston position, showing significant improvement with delayed timing. Hydrogen (H 2 ) and ethane (C 2 H 6 ) were added to simulate recycle from a downstream synthesis reactor and realistic natural gas compositions, respectively. Adding these gases yielded a stable combustion up to hydrocarbon‐air equivalence ratios ( ϕ HC ) of 2.8 with COV nimep < 5 %. Ethane concentrations (with respect to methane) of up to 0.2 L/L (20 vol%) (with and without H 2 ) produced robust and stable combustions, demonstrating that the engine can be operated across a range of natural gas compositions. Engine exhaust soot concentrations demonstrated elevated values at ϕ HC > 2.4, but < 1 mg/L below these equivalence ratios. These results demonstrate that the engine reformer could be a key component of a compact gas‐to‐liquids synthesis plant by highlighting the operating conditions under which high gas conversion, high H 2‐ to‐CO ratios close to 2.0, and low soot production are possible.

Lim, Emmanuel G.↗
DOE OSTI2014

Design of gem -Difluoro- bis -Tetrahydrofuran as P2 Ligand for HIV-1 Protease Inhibitors to Improve Brain Penetration: Synthesis, X-ray Studies, and Biological Evaluation

The structure–based design, synthesis, biological evaluation, and X–ray structural studies of fluorine–containing HIV–1 protease inhibitors are described. The synthesis of both enantiomers of the gem–difluoro–bis–THF ligands was carried out in a stereoselective manner using a Reformatskii–Claisen reaction as the key step. Optically active ligands were converted into protease inhibitors. Two of these inhibitors, (3R,3aS,6aS)–4,4–difluorohexahydrofuro[2,3–b]furan–3–yl(2S,3R)–3–hydroxy–4–((N–isobutyl–4–methoxyphenyl)sulfonamido)–1–phenylbutan–2–yl) carbamate (3) and (3R,3aS,6aS)–4,4–difluorohexahydrofuro[2,3–b]furan–3–yl(2S,3R)–3–hydroxy–4–((N–isobutyl–4–aminophenyl)sulfonamido)phenylbutan–2–yl) carbamate (4), exhibited HIV–1 protease inhibitory K i values in the picomolar range. Both 3 and 4 showed very potent antiviral activity, with respective EC 50 values of 0.8 and 3.1 nM against the laboratory strain HIV–1 LAI . The two inhibitors exhibited better lipophilicity profiles than darunavir, and also showed much improved blood–brain barrier permeability in an in vitro model. A high–resolution X–ray structure of inhibitor 4 in complex with HIV–1 protease was determined, revealing that the fluorinated ligand makes extensive interactions with the S2 subsite of HIV–1 protease, including hydrogen bonding interactions with the protease backbone atoms. Moreover, both fluorine atoms on the bis–THF ligand formed strong interactions with the flap Gly 48 carbonyl oxygen atom.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Design, Synthesis, Biological Evaluation, and X-ray Studies of HIV-1 Protease Inhibitors with Modified P2' Ligands of Darunavir

The structure–based design, synthesis, and biological evaluation of a series of nonpeptidic HIV–1 protease inhibitors with rationally designed P2' ligands are described. The inhibitors are designed to enhance backbone binding interactions, particularly at the S2' subsite. Synthesis of inhibitors was carried out efficiently. The stereochemistry of alcohol functionalities of the P2' ligands was set by asymmetric reduction of the corresponding ketone using (R,R)– or (S,S)–Noyori catalysts. A number of inhibitors displayed very potent enzyme inhibitory and antiviral activity. Inhibitors 3g and 3h showed enzyme Ki values of 27.9 and 49.7 pm and antiviral activity of 6.2 and 3.9 nm, respectively. These inhibitors also remained quite potent against darunavir–resistant HIV–1 variants. In conclusion, an X–ray structure of inhibitor 3g in complex with HIV–1 protease revealed key interactions in the S2' subsite.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2013

Synthesis and Characterization of Gold Clusters Ligated with 1,3-Bis(dicyclohexylphosphino)propane

In this multidisciplinary study we combine chemical reduction synthesis of novel gold clusters in solution with high-resolution analytical mass spectrometry (MS) to gain insight into the composition of the gold clusters and how their size, ionic charge state and ligand substitution influences their gas-phase fragmentation pathways. Ultra small cationic gold clusters ligated with 1,3-bis(dicyclohexylphosphino)propane (DCPP) were synthesized for the first time and introduced into the gas phase using electrospray ionization (ESI). Mass-selected cluster ions were fragmented employing collision induced dissociation (CID) and the product ions were analysed using MS. The solutions were found to contain the multiply charged cationic gold clusters Au9L43+, Au13L53+, Au6L32+, Au8L32+ and Au10L42+ (L = DCPP). The gas-phase fragmentation pathways of these cluster ions were examined systematically employing CID combined with MS. In addition, CID experiments were performed on related gold clusters of the same size and ionic charge state but capped with 1,3-bis(diphenylphosphino)propane (DPPP) ligands containing phenyl functional groups at the two phosphine centers instead of cyclohexane rings. It is shown that this relatively small change in the molecular substitution of the two phosphine centers in diphosphine ligands (C6H11 versus C6H5) exerts a pronounced influence on the size of the species that are preferentially formed in solution during reduction synthesis as well as the gas-phase fragmentation channels of otherwise identical gold cluster ions. The mass spectrometry results indicate that in addition to the length of the alkyl chain between the two phosphine centers, the substituents at the phosphine centers also play a crucial role in determining the composition, size and stability of diphosphine ligated gold clusters synthesized in solution.

Johnson, Grant E.↗
DOE OSTI2019

An Improved Strategy for the Chemical Synthesis of 3′,5′‐Cyclic Diguanylic Acid

Abstract The physiological functions of c‐di‐GMP and its involvement in many key processes led to its recognition as a major and ubiquitous bacterial second messenger. Aside from being a bacterial signaling molecule, c‐di‐GMP is also an immunostimulatory molecule capable of inducing innate and adaptive immune responses through maturation of immune mammalian cells. Given the broad biological functions of c‐di‐GMP and its potential applications as a nucleic‐acid‐based drug, the chemical synthesis of c‐di‐GMP has drawn considerable interest. An improved phosphoramidite approach to the synthesis of c‐di‐GMP is reported herein. The synthetic approach is based on the use of a 5′‐ O ‐formyl protecting group, which can be rapidly and chemoselectively cleaved from a key dinucleotide phosphoramidite intermediate to enable a cyclocondensation reaction leading to a fully protected c‐di‐GMP product in a yield ∼80%. The native c‐di‐GMP is isolated, after complete deprotection, in an overall yield of 36% based on the commercial ribonucleoside used as starting material. © 2019 by John Wiley & Sons, Inc.

Grajkowski, Andrzej↗
DOE OSTI2014

Directed Synthesis of Nanoporous Carbons from Task-Specific Ionic Liquid Precursors for the Adsorption of CO 2

Postcombustion CO 2 capture has become a key component of greenhouse-gas reduction as anthropogenic emissions continue to impact the environment. In this paper, we report a one-step synthesis of porous carbon materials using a series of task-specific ionic liquids for the adsorption of CO 2 . By varying the structure of the ionic liquid precursor, we were able to control pore architecture and surface functional groups of the carbon materials in this one-step synthesis process leading to adsorbents with high CO 2 sorption capacities (up to 4.067 mmol g -1 ) at 0 °C and 1 bar. Finally, added nitrogen functional groups led to high CO 2 /N 2 adsorption-selectivity values ranging from 20 to 37 whereas simultaneously the interaction energy was enhanced relative to carbon materials with no added nitrogen.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

A Solvent-Free Synthesis of Lignin-Derived Renewable Carbon with Tunable Porosity for Supercapacitor Electrodes

Synthesis of multiphase materials from lignin, a biorefinery coproduct, offers limited success owing to the inherent difficulty in controlling dispersion of these renewable hyperbranched macromolecules in the product or its intermediates. Effective use of the chemically reactive functionalities in lignin, however, enables tuning morphologies of the materials. Here in this study, we bind lignin oligomers with a rubbery macromolecule followed by thermal crosslinking to form a carbon precursor with phase contrasted morphology at submicron scale. The solvent-free mixing is conducted in a high-shear melt mixer. With this, the carbon precursor is further modified with potassium hydroxide for a single-step carbonization to yield activated carbon with tunable pore structure. A typical precursor with 90 % lignin yields porous carbon with 2120 m 2 g -1 surface area and supercapacitor with 215 F g -1 capacitance. Lastly, the results show a simple route towards manufacturing carbon-based energy-storage materials, eliminating the need for conventional template synthesis.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Defect Control in the Synthesis of 2 D MoS 2 Nanosheets: Polysulfide Trapping in Composite Sulfur Cathodes for Li–S Batteries

One of the inherent challenges with Li–S batteries is polysulfide dissolution, in which soluble polysulfide species can contribute to the active material loss from the cathode and undergo shuttling reactions inhibiting the ability to effectively charge the battery. Prior theoretical studies have proposed the possible benefit of defective 2 D MoS 2 materials as polysulfide trapping agents. Herein the synthesis and thorough characterization of hydrothermally prepared MoS 2 nanosheets that vary in layer number, morphology, lateral size, and defect content are reported. Here, the materials were incorporated into composite sulfur–based cathodes and studied in Li–S batteries with environmentally benign ether–based electrolytes. Through directed synthesis of the MoS 2 additive, the relationship between synthetically induced defects in 2 D MoS 2 materials and resultant electrochemistry was elucidated and described.

25 ENERGY STORAGE↗
DOE OSTI2020

Chemical–Switching Strategy for Synthesis and Controlled Release of Norcantharimides from a Biomass–Derived Chemical

Catalytic strategies were developed to synthesize and release chemicals for applications in fine chemicals, such as drugs and polymers, from a biomass-derived chemical, 5-hydroxymethyl furfural (HMF). The combination of the diene and aldehyde functionalities in HMF enabled catalytic production of acetalized HMF derivatives with diol or epoxy reactants to allow reversible synthesis of norcantharimide derivatives upon Diels-Alder reaction with maleimides. Reverse-conversion of the acetal group to an aldehyde yielded mismatches of the molecular orbitals in norcantharimides to trigger retro Diels-Alder reaction at ambient temperatures and released reactants from the coupled molecules under acidic conditions. In conclusion, these strategies provide for the facile synthesis and controlled release of high-value chemicals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Morphology‐controlled synthesis of multi‐metal‐based spinel oxide nanocatalysts and their performance for oxygen reduction

Abstract We present a one‐pot colloidal synthesis method for producing monodisperse multi‐metal (Co, Mn, and Fe) spinel nanocrystals (NCs), including nanocubes, nano‐octahedra, and concave nanocubes. This study explores the mechanism of morphology control, showcasing the pivotal roles of metal precursors and capping ligands in determining the exposed crystal planes on the NC surface. The cubic spinel NCs, terminated with exclusive {100}‐facets, demonstrate superior electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline media compared to their octahedral and concave cubic counterparts. Specifically, at 0.85 V, (CoMn)Fe 2 O 4 spinel oxide nanocubes achieve a high mass activity of 23.9 A/g and exhibit excellent stability, highlighting the promising ORR performance associated with {100}‐facets of multi‐metal spinel oxides over other low‐index and high‐index facets. Motivated by exploring the correlation between ORR performance and surface atom arrangement (active sites), surface element composition, as well as other factors, this study introduces a prospective approach for shape‐controlled synthesis of advanced spinel oxide NCs. It underscores the significance of catalyst shape control and suggests potential applications as nonprecious metal ORR electrocatalysts.

Li, Can↗
DOE OSTI2017

Nitrogen-doped graphene catalysts: High energy wet ball milling synthesis and characterizations of functional groups and particle size variation with time and speed

Nitrogen-doped graphene (N-G) catalyst emerges as one of the promising non-platinum group metal (non-PGM) catalysts with the advantages of low cost, high oxygen reduction reaction (ORR) activity, stability, and selectivity to replace expensive PGM catalysts in electrochemical systems. This research investigated nanoscale high energy wet (NHEW) ball milling for the synthesis of N-G catalysts to make conventional problems such as sintering or localized overheating issues negligible. The successful synthesis of N-G catalysts with comparable catalytic performance to 10 wt% Pt/C by using this method has been published. This paper focuses on understanding the effect of grinding speed and grinding time on the particle size and chemical state of N-G catalysts through the physical and chemical characterization. The research result shows that (1) the final particle size, nitrogen doping percentage, and nitrogen bonding composition of synthesized N-G catalysts are predictable and controllable by adjusting the grinding time, the grinding speed, and other relative experimental parameters; (2) the final particle size of N-G catalysts could be estimated from the derived relation between the cracking energy density and the particle size of ground material in the NHEW ball milling process with specified experimental parameters; and (3) the chemical composition of N-G catalysts synthesized by NHEW ball milling is controllable by adjusting the grinding time and grinding speed.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2012

Synthesis of N1-tritylethane-1,1,2,2-d4-1,2-diamine: a novel mono-protected C-deuterated ethylenediamine synthon

A convenient and high-yield synthesis for N1-tritylethane-1,1,2,2-d4-1,2-diamine, a novel mono-protected ethylenediamine-C-d4, is reported. N1-tritylethane-1,1,2,2-d4-1,2-diamine was prepared in three steps from ethylene oxide-d4 in a combined yield in the range 68-76%. Also reported is a synthesis of ethylenediamine-C-d4 in two steps from 1,2-dibromoethane-d4 in a combined yield in the range 61-65%.

deuterated ethylenediamine↗
DOE OSTI2014

Comparing linear and cyclic synthetic homopolypeptides: Synthesis and molecular characterization

We report the synthesis and molecular characterization of a linear and a cyclic homopolypeptide of protected l-tyrosine. The successful synthesis of polypeptides exhibiting the desired linear and cyclic structures through various characterization methods such as high temperature gel permeation chromatography, Fourier transform infrared spectroscopy, proton and carbon nuclear magnetic resonance spectroscopy, mass spectrometry, dynamic light scattering, differential scanning calorimetry, and thermogravimetric analysis was verified in this work. Our results are very promising especially if such cyclic materials will be potentially used as carriers for drug delivery, either through conjugation with specific ligands or directly through the functional hydroxyl groups of the monomeric units of poly(l-Tyr) after deprotection.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Size‐Tunable Synthesis of Hollow Gold Nanospheres through Control of Reaction Temperature

Here, it is demonstrated that the size tunable hollow gold nanospheres (HGNs) of ≈24–122 nm in diameter can be facilely achieved by controlling a signal parameter, reaction temperature, in the synthesis. The varied particle sizes of HGNs result in highly tunable surface plasmon resonance (SPR) absorption in the entire visible to near infrared region of the spectrum, with maximum peak position from 565 to 850 nm when the reaction temperature is varied from 80 to 10 °C. The particle size and structural properties are determined using dynamic light scattering, transmission‐mode scanning electron microscopy, and high‐resolution transmission electron microscopy. The optical properties are characterized using UV–vis spectroscopy. A mechanism behind the temperature‐dependent HGN synthesis is explained by the thermodynamics of homogeneous nuclei formation of the cobalt scaffold. Discrete dipole approximation calculations are performed to simulate the SPR spectrum and provide insight into the relation between the SPR absorption and structural details of the HGNs. This study demonstrates a simple yet effective method based on temperature control for synthesizing produce size tunable HGNs with varying properties of interest for different applications.

Pu, Ying‐Chih↗
DOE OSTI2018

Synthesis and Evaluation of 3-Picrylamino-1,2,4-Triazole (PATO) Formulations

3–Picrylamino–1,2,4–triazole (PATO) is a thermally stable explosive invented at Los Alamos National Laboratory (LANL) almost half a century ago. Despite a rapid and high yielding synthesis, performance data for this promising explosive are scant. We prepared material using Coburn's synthesis, and discovered that the particle size distribution and morphology leads to difficulty in pressing formulations to high density. Three formulations were made using glycidyl azide polymer (GAP), FK–800, and Estane 5703/nitroplasticizer (NP) as binders. The maximum pressed density of these formulations was 89 % of theoretical maximum density (TMD). We determined detonation velocity and, for the FK–800 formulation, detonation pressure. Furthermore, the performance of PATO is similar to TATB at equivalent pressed density.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗