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At least 1,207 records · Page 67
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on H9BrO4 by Materials Project

H2OH7O3Br crystallizes in the monoclinic P2_1 space group. The structure is zero-dimensional and consists of four water molecules and four H7O3Br clusters. In two of the H7O3Br clusters, there are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- and one Br1- atom. The H–O bond length is 1.01 Å. The H–Br bond length is 2.13 Å. In the fourth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.07 Å) and one longer (1.45 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.09 Å) and one longer (1.40 Å) H–O bond length. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. Br1- is bonded in a distorted single-bond geometry to one H1+ atom. In two of the H7O3Br clusters, there are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.05 Å) and one longer (1.47 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- and one Br1- atom. The H–O bond length is 1.01 Å. The H–Br bond length is 2.16 Å. In the fifth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.09 Å) and one longer (1.40 Å) H–O bond length. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three H1+ atoms. Br1- is bonded in a 1-coordinate geometry to one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H7NO6 by Materials Project

NO3H7O3 crystallizes in the monoclinic P2_1 space group. The structure is zero-dimensional and consists of four nitric acid molecules and four H7O3 clusters. In two of the H7O3 clusters, there are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.09 Å) and one longer (1.37 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.49 Å) H–O bond length. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three H1+ atoms. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In two of the H7O3 clusters, there are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.20 Å) and one longer (1.23 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the seventh H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.63 Å) H–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to three H1+ atoms. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb19O3 by Materials Project

Rb(Rb6O)3 is Copper structured and crystallizes in the cubic Fm-3c space group. The structure is zero-dimensional and consists of eight rubidium molecules and twenty-four Rb6O clusters. In each Rb6O cluster, there are two inequivalent Rb sites. In the first Rb site, Rb is bonded in a single-bond geometry to one O atom. The Rb–O bond length is 2.63 Å. In the second Rb site, Rb is bonded in a single-bond geometry to one O atom. The Rb–O bond length is 2.95 Å. O is bonded in an octahedral geometry to six Rb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO2 by Materials Project

FeO2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four iron dihydroxide molecules. Fe is bonded in a distorted linear geometry to two equivalent O atoms. Both Fe–O bond lengths are 1.32 Å. O is bonded in a single-bond geometry to one Fe atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Charged- and Multi-Exciton Dynamics in Colloidal Quantum Dot Molecules

Multicarrier states in quantum dots are confined to small volumes, resulting in increased nonradiative Auger recombination rates with implications for different optoelectronic applications. Recently, the fusion of two core-shell quantum dots into a dimer has provided a new physical landscape for multiexciton states, since the excitons may share a core (intradot, localized) or occupy different cores (interdot, segregated). Here, in this study, we employ transient absorption spectroscopy to investigate the multiexciton dynamics in coupled quantum dot dimers. We observe that multiexciton populations in the dimers live significantly longer in comparison to the parent monomers, in contrast to the single exciton regime. A kinetic model that accounts for the statistical differences between monomers and dimers reveals that, while intradot multiexcitons show Auger rates similar to the monomers, interdot states have reduced Auger rates. These results pave the way for the rational design of new quantum dot molecules with tailored multiexciton properties.

Auger recombination↗
DOE OSTI2025

Iron Single‐Atom Catalyzed N‐Alkylation of Amines with Alcohols via Solvent‐Free Borrowing Hydrogen Strategy

Abstract Industrial hydrogenation is a pivotal process in chemical synthesis. However, it has significant drawbacks, including high cost, safety risks associated with the use of molecular hydrogen gas, and substantial energy demands due to the need for elevated temperatures and pressures to achieve satisfactory yields. The borrowing hydrogen synthesis, which enables the transfer of hydrogen between molecules, offers a promising approach for green, one‐pot synthesis of industrially important chemicals and intermediates. Despite its potential, the broad application remains limited due to the reliance on toxic solvents, expensive noble metal catalysts, and the still restricted efficiency and substrate scope. In this study, the first solvent‐free strategy for theN‐alkylation of amines with alcohols is presented, employing an N‐doped graphene‐supported Fe single‐atom catalyst (Fe SA @N‐G; 1.06 wt.%). This approach achieves superior conversion and selectivity (up to 99%) along with record values for turnover number (TON, 1032.7) and turnover frequency (TOF, 413.1 h -1 ) for the coupling reaction of aniline with benzyl alcohol, surpassing all previously reported catalysts. DFT calculations, combined with experimental data, elucidated the reaction mechanism and identified the Fe 1 (III)‐N 4 active site participating in Fe‐H hydride transfer and containing two pyrrolic and two pyridinic nitrogens bound to the Fe center. The developed technology is further supported by the catalyst's excellent scalability, reusability, and performance under continuous‐flow conditions. Additionally, the exceptional efficiency of the single‐atom catalyst is demonstrated across more than 50 substrates, including reactions involving both aliphatic and aromatic amines with aliphatic and aromatic alcohols. The industrial applicability of this technology is validated through the synthesis of pharmaceutically relevant compounds, including stimulant drugs, antihistamines, and pharmaceutical intermediates.

Chemistry↗
DOE OSTI2020

Lipid sponge droplets as programmable synthetic organelles

Living cells segregate molecules and reactions in various subcellular compartments known as organelles. Spatial organization is likely essential for expanding the biochemical functions of synthetic reaction systems, including artificial cells. Many studies have attempted to mimic organelle functions using lamellar membrane-bound vesicles. However, vesicles typically suffer from highly limited transport across the membranes and an inability to mimic the dense membrane networks typically found in organelles such as the endoplasmic reticulum. Here, we describe programmable synthetic organelles based on highly stable nonlamellar sponge phase droplets that spontaneously assemble from a single-chain galactolipid and nonionic detergents. Due to their nanoporous structure, lipid sponge droplets readily exchange materials with the surrounding environment. In addition, the sponge phase contains a dense network of lipid bilayers and nanometric aqueous channels, which allows different classes of molecules to partition based on their size, polarity, and specific binding motifs. The sequestration of biologically relevant macromolecules can be programmed by the addition of suitably functionalized amphiphiles to the droplets. We demonstrate that droplets can harbor functional soluble and transmembrane proteins, allowing for the colocalization and concentration of enzymes and substrates to enhance reaction rates. Droplets protect bound proteins from proteases, and these interactions can be engineered to be reversible and optically controlled. Our results show that lipid sponge droplets permit the facile integration of membrane-rich environments and self-assembling spatial organization with biochemical reaction systems.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Restructuring and integrity of molecular catalysts in electrochemical CO 2 reduction

Electrocatalysts that start a reaction as molecules do not always end the reaction as molecules, and even when they do, they might not be molecules during catalysis. In this Perspective, we discuss knowledge learned from the study of Cu-based molecularly structured electrocatalysts––including metal coordination complexes, metal-organic frameworks, single-atom catalysts, and polymeric materials––that restructure under electrochemical CO 2 reduction reactions. Recent reports are summarized with an emphasis on the nature and significance of post-mortem and in situ characterization for the proper identification of active sites. We demonstrate that molecular and material structures determine whether electrocatalysts restructure and how they restructure, that understanding of restructuring processes can help us identify active sites for catalysis, and that this knowledge can be leveraged to design precatalysts that generate highly active catalysts under reaction conditions. In addition, we provide recommended practices for studying the integrity of heterogeneous molecular catalysts during and after CO 2 reduction reactions.

CO2 reduction↗
DOE OSTI2023

Exploring Parameter Redundancy in the Unitary Coupled-Cluster Ansätze for Hybrid Variational Quantum Computing

One of the commonly used chemical-inspired approaches in variational quantum computing is the unitary coupled-cluster (UCC) ansatze. Despite being a systematic way of approaching the exact limit, the number of parameters in the standard UCC ansatze exhibits unfavorable scaling with respect to the system size, hindering its practical use on near-term quantum devices. Efforts have been taken to propose some variants of UCC ansatze with better scaling. In this paper we explore the parameter redundancy in the preparation of unitary coupled-cluster singles and doubles (UCCSD) ansatze employing spin-adapted formulation, small amplitude filtration, and entropy-based orbital selection approaches. Numerical results of using our approach on some small molecules have exhibited a significant cost reduction in the number of parameters to be optimized and in the time to convergence compared with conventional UCCSD-VQE simulations. Further, we also discuss the potential application of some machine learning techniques in further exploring the parameter redundancy, providing a possible direction for future studies.

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

Cryo-EM structures of HIV-1 trimer bound to CD4-mimetics BNM-III-170 and M48U1 adopt a CD4-bound open conformation

Human immunodeficiency virus-1 (HIV-1), the causative agent of AIDS, impacts millions of people. Entry into target cells is mediated by the HIV-1 envelope (Env) glycoprotein interacting with host receptor CD4, which triggers conformational changes allowing binding to a coreceptor and subsequent membrane fusion. Small molecule or peptide CD4-mimetic drugs mimic CD4’s Phe43 interaction with Env by inserting into the conserved Phe43 pocket on Env subunit gp120. Here, we present single-particle cryo-EM structures of CD4-mimetics BNM-III-170 and M48U1 bound to a BG505 native-like Env trimer plus the CD4-induced antibody 17b at 3.7 Å and 3.9 Å resolution, respectively. CD4-mimetic-bound BG505 exhibits canonical CD4-induced conformational changes including trimer opening, formation of the 4-stranded gp120 bridging sheet, displacement of the V1V2 loop, and formation of a compact and elongated gp41 HR1C helical bundle. We conclude that CD4-induced structural changes on both gp120 and gp41 Env subunits are induced by binding to the gp120 Phe43 pocket.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Interconnected nanoconfining pore networks enhance catalyst CO 2 interaction in electrified reactive capture

Systems that sequentially capture and upgrade CO 2 from air to fuels/fuel-intermediates, such as syngas and ethylene, rely on an energy-intensive CO 2 release process. Electrified reactive capture systems transform CO 2 obtained directly from carbonate capture liquid into products. Previous reactive capture systems show a decline in Faradaic efficiencies (FE) at current densities above 200 mA/cm 2 . Here we show the chemical origins of this problem, finding that prior electrocatalyst designs failed to arrest, activate, and reduce in situ-generated CO 2 (i-CO 2 ) before it traversed the catalyst layer and entered the tailgas stream. We develop a templated synthesis to define pore structures and the sites of Ni single atoms, and find that carbon-nitrogen-based nanopores are effective in accumulating i-CO 2 via short-range, non-electrostatic interactions between CO 2 molecules and the nanochannel walls. These interactions confine and enrich i-CO 2 within the pores, enhancing its binding and activation. We report as a result carbonate electrolysis at 300 mA/cm 2 with FE to CO of 50% ± 3%, and with <1% CO 2 in the tailgas outlet stream. This corresponds to a projected energy efficiency (EE) to 2:1 syngas of 46% at 300 mA/cm 2 when H 2 is added using a water electrolyzer.

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

Coupled Cluster Downfolding Methods: the effect of double commutator terms on the accuracy of ground-state energies

Downfolding coupled cluster (CC) techniques have recently been introduced into quantum chemistry as a tool for the dimensionality reduction of the many-body quantum problem. As opposed to earlier formulations in physics and chemistry based on the concept of effective Hamiltonians, the appearance of the downfolded Hamiltonians is a natural consequence of the single-reference exponential parametrization of the wave function. In this paper, we discuss the impact of higher-order terms originating in double commutators. In analogy to previous studies, we consider the case when only one- and two-body interactions are included in the downfolded Hamiltonians. We demonstrate the efficiency of the many-body expansions involving single and double commutators for the unitary extension of the downfolded Hamiltonians on the example of the beryllium atom, and bond-breaking processes in the Li2 and H2O molecules. For the H2O system, we also analyze energies obtained with downfolding procedures as functions of the active space size.

quantum computing, quantum algorithms, electronic ↗
DOE OSTI2020

Materials Data on SO2 by Materials Project

SO2 is Copper structured and crystallizes in the orthorhombic Aea2 space group. The structure is zero-dimensional and consists of four sulfur dioxide molecules. S4+ is bonded in a bent 120 degrees geometry to two equivalent O2- atoms. Both S–O bond lengths are 1.45 Å. O2- is bonded in a single-bond geometry to one S4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cl2O by Materials Project

Cl2O crystallizes in the tetragonal I4_1/amd space group. The structure is zero-dimensional and consists of eight chlorine monoxide molecules. O is bonded in a bent 120 degrees geometry to two equivalent Cl atoms. Both O–Cl bond lengths are 1.73 Å. Cl is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H30S2O21 by Materials Project

H9O4H7O3(H7SO7)2 crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two hydrogen tetrahydrate molecules, two H7O3 clusters, and four H7SO7 clusters. In each H7O3 cluster, there are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.07 Å) and one longer (1.41 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three H1+ atoms. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In each H7SO7 cluster, there are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fifth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.61 Å) H–O bond length. In the sixth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.60 Å) H–O bond length. In the seventh H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.14 Å) and one longer (1.31 Å) H–O bond length. S6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of S–O bond distances ranging from 1.49–1.51 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to three H1+ atoms. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the fourth O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one S6+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one H1+ and one S6+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to one S6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SF4 by Materials Project

SF4 is Silicon tetrafluoride-like structured and crystallizes in the tetragonal I-42m space group. The structure is zero-dimensional and consists of two sulfur tetrafluoride molecules. S4+ is bonded in a distorted trigonal pyramidal geometry to four equivalent F1- atoms. All S–F bond lengths are 1.73 Å. F1- is bonded in a single-bond geometry to one S4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B13N2 by Materials Project

B13N2 crystallizes in the trigonal R-3m space group. The structure is zero-dimensional and consists of eighteen boron, metallic molecules and three B7N2 clusters. In each B7N2 cluster, there are two inequivalent B+0.23+ sites. In the first B+0.23+ site, B+0.23+ is bonded in a single-bond geometry to one N+1.50- atom. The B–N bond length is 1.57 Å. In the second B+0.23+ site, B+0.23+ is bonded in a linear geometry to two equivalent N+1.50- atoms. Both B–N bond lengths are 1.43 Å. N+1.50- is bonded to four B+0.23+ atoms to form corner-sharing NB4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NO2 by Materials Project

NO2 crystallizes in the cubic I2_13 space group. The structure is zero-dimensional and consists of twelve nitrous acid molecules. N is bonded in a bent 120 degrees geometry to two equivalent O atoms. Both N–O bond lengths are 1.21 Å. O is bonded in a single-bond geometry to one N atom.

36 MATERIALS SCIENCE↗