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Selective CO 2 Reduction by Bis(bipyridine)cobalt(II) Catalysts: The Role of Pendant Pyridine as a Proton Acceptor
Electrochemical CO 2 reduction reaction (CO 2 RR) catalyzed by molecular earth-abundant metal catalysts is a promising strategy to convert CO 2 into value-added products. One recent trend in this field has been focusing on the rational design of catalysts by incorporating redox-active ligands and modifying the secondary coordination sphere (SCS) to achieve efficient and selective CO 2 RR. Herein, we report a series of Co bis(bipyridine) catalysts featuring various dangling groups, such as pyridine, tertiary amine, or butyl, in the secondary coordination sphere (Co-PyMe, Co-Py, Co-PrN, and Co-Bu). Efficient, selective electrocatalytic CO 2 RR was achieved by the complexes after the generation of triply reduced intermediate consisting of a Co I center and a dianionic ligand, producing CO as the major product and trace amount of H 2 . Strong correlations with the identity of dangling groups and turnover frequency (TOF) have been observed, in which Co-PyMe displayed the highest TOF (1086 s –1 in MeCN/H 2 O). Mechanistic studies indicated that the acceleration of CO 2 RR with pyridine-functionalized catalysts were derived from the protonation of pyridine dangling groups which participated as weak acids in the H-bonding network with exogenous proton sources, stabilizing CO 2 -bound intermediates and facilitating proton transfer. In addition, precatalytic CO 2 binding and activation at the third reduction (−2.1 V) was revealed by CV and SEC-IR studies. The resultant doubly reduced CO-bound species acted as a trapping state which inhibited CO 2 RR electrocatalysis. Regeneration of active species was accessed via reductive dissociation of CO at a more negative potential. In conclusion, this study highlights the combined effects of redox-active ligands and pyridine/pyridinium as SCS groups on CO 2 RR catalysis and provides design principles for future development of CO 2 RR catalysts utilizing pyridine/pyridiniums as SCS functional groups to fine-tune the catalytic activity.
Permanganometric Titration for the Quantification of Purified Bis(2,4,4-trimethylpentyl)dithiophosphinic Acid in n -Dodecane
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Atomistic Insights into Structure and Dynamics of Neodymium(III) Complexation with a Bis-lactam Phenanthroline Ligand in the Organic Phase
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Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry Analysis of Eutectic Bis(2,2-dinitropropyl) Acetal/Formal Degradation Profile: Nontargeted Identification of Antioxidant Derivatives
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Bis(diisopropylamino)cyclopropenium-arene Cations as High Oxidation Potential and High Stability Catholytes for Non-aqueous Redox Flow Batteries
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Complexation of Pluronic L62 (EO 6 )–(PO 34 )–(EO 6 )/aerosol-OT (sodium bis(2-ethylhexyl)sulfosuccinate) in aqueous solutions investigated by small angle neutron scattering
Herein, we investigate the phase behaviours of Pluronic L62 in aqueous solution in the presence of aerosol-OT (AOT) molecules by small angle neutron scattering (SANS). The presence of AOT significantly changes the micellization phenomenon of L62 micelles in aqueous solution, including their critical micelle temperature (CMT), global size, and asphericity. The origin of these observations is attributed to the complexation between the neutral L62 surfactants and the ionic AOT molecules, which additionally provides charge to the mixed micelles: we analyse the data and extract meaningful information using the Ornstein–Zernike integral formalism. As a result, we observe that the co-micellization of L62 and AOT is very stable across a wide temperature range.
Back Cover image and language for "Evaluating the Bis-isoxazole Core for Energetic Heterocyclic-Based Oligomers"
Development of energetic polymers is at the forefront of the energetics research enterprise. Formulations having high energy density as well as robust safety are goals that can be realized with implementation of new energetic polymers that target performance and mechanical properties. Presented herein are a series of oligomers synthesized from the small molecule BIDO (1) as our group's first attempt at making heterocyclic based energetic polymers without sensitive explosophores. Crystallographic investigation of the BIDO core with surrogate addends demonstrated the significant stacking ability of the BIDO core. Synthesis of four unique oligomers (3–6) is presented and characterized by spectroscopic and thermochemical measurements. Polymerization of 6 was demonstrated and tested for T g and thermal sensitivity, and Shore A hardness. The polymer 7 exhibits a T g value (-18 °C), close to the operating range of other energetic materials, a Shore A hardness of 81, and thermally stable up to 320 °C.
Convergent access to bis-1,2,4-triazinyl-2,2′-bipyridines (BTBPs) and 2,2′-bipyridines via a Pd-catalyzed Ullman-type reaction
Access to functionalized BTBP complexants through a reductive coupling strategy decreases linearity of common synthetic strategies towards these relevant materials for separations.
1,2-Addition and cycloaddition reactions of niobium bis(imido) and oxo imido complexes
Another slice of pi: the addition of a second π-donor ligand engenders 1,2-addition and [2 + 2] cycloaddition reactivity across Nb-imido and Nb-oxo bonds.
A novel catalytic heme cofactor in SfmD with a single thioether bond and a bis -His ligand set revealed by a de novo crystal structural and spectroscopic study
The de novo crystal structure of SfmD reveals a novel c -type heme cofactor for promoting a monooxygenation reaction in the biosynthetic pathway of saframycin A.
Direct metal–carbon bonding in symmetric bis(C–H) agostic nickel( i ) complexes
Symmetric Ni( i ) agostic complexes reveal an unusual mode of bonding that is dominated by direct carbon-to-metal charge transfer.
Actinide arene-metalates: 2. A neutral uranium bis(anthracenide) sandwich complex and elucidation of its electronic structure
Reaction of [UI 2 (HMPA) 4 ]I with potassium anthracenide gives the unprecedented arenide-sandwich complex U(η 6 -C 14 H 10 )(η 4 -C 14 H 10 )(HMPA) 2 . CASSCF calculations indicate the U–C bonding to solely consist of π-interactions.
Tellurolate: an effective Te-atom transfer reagent to prepare the triad of group 5 metal bis(tellurides)
We show in this work how lithium tellurolate Li(X) n TeCH 2 SiMe 3 (X = THF, n = 1, 1; X = 12- crown -4, n = 2, 2), can serve as an effective Te-atom transfer reagent to all group 5 transition metal halide precursors irrespective of their oxidation state.
Intermolecular C–H silylations of arenes and heteroarenes with mono-, bis-, and tris(trimethylsiloxy)hydrosilanes: control of silane redistribution under operationally diverse approaches
Operationally diverse C–H silylations of (hetero) arenes with a broad silane scope are reported. The control of silane redistribution improves overall catalytic efficiency, affording the various arylsiloxysilanes useful for polysiloxane materials.
Uncovering intramolecular singlet fission at the root of the dual fluorescence of 1,4-bis( p -nitro-β-styryl)benzene in solution
The exploration of singlet fission (SF) promises a pathway to many leaps forward including more efficient solar energy extraction and, more recently, organic-based quantum computing.