Results for “coordinated” — Page 5

NASA NTRS2017

Time-Coordination Strategies and Control Laws for Multi-Agent Unmanned Systems

Time-critical coordination tools for unmanned systems can be employed to enforce the type of temporal constraints required in terminal control areas, ensure minimum distance requirements among vehicles are satisfied, and successfully perform coordinated missions. In comparison with previous literature, this paper presents an ampler spectrum of coordination and temporal specifications for unmanned systems, and proposes a general control law that can enforce this range of constraints. The constraint classification presented con- siders the nature of the desired arrival window and the permissible coordination errors to define six different types of time-coordination strategies. The resulting decentralized coordination control law allows the vehicles to negotiate their speeds along their paths in response to information exchanged over the communication network. This control law organizes the different members in the fleet hierarchically per their behavior and informational needs as reference agent, leaders, and followers. Examples and simulation results for all the coordination strategies presented demonstrate the applicability and efficacy of the coordination control law for multiple unmanned systems.

Puig-Navarro, Javier↗

DOE OSTI2023

Coordination Chemistry as a Universal Strategy for a Controlled Perovskite Crystallization

The most efficient and stable perovskite solar cells (PSCs) are made from complex mixture of precursors, which are practically always dissolved in combinations of the volatile (and toxic) N, N-Dimethylformamide (DMF), and the non-volatile (and green) dimethyl sulfoxide (DMSO) solvents. Typically, to then form a thin film, an extreme oversaturation of the perovskite precursor is initiated to trigger nucleation sites, e.g. by vacuum, an airstream or a so-called antisolvent. Unfortunately, most such oversaturation triggers do not expel the lingering (and highly coordinating) DMSO, which is highly coordinating, from the thin films; this detrimentally affects long-term stability. Here, for the first time, we introduce (the green) dimethyl sulfide (DMS) as a novel nucleation trigger for perovskite films combining, uniquely, high coordination and high vapor pressure. More precisely, DMS coordinates more strongly than all currently used solvents, hence replacing them, including DMSO, effectively during film formation. Crucially, DMS also has among the highest vapor pressures reported in literature, thus effectively leaving the thin film shortly after formation. This gives DMS a universal scope: DMS replaces other solvents by coordinating more strongly and removes itself once the film formation is finished. To demonstrate this novel coordination chemistry approach, we process MAPbI 3 PSCs, typically dissolved in hard-to-remove (and green) DMSO achieving 21.6% efficiency, among the highest reported efficiencies for this system. To confirm the universality of our strategy, we tested DMS for FAPbI 3 as another composition, which showed higher efficiency of 23.5% compared to 20.9% for fabricated device with CB. Finally, this work provides a universal strategy to control perovskite crystallization using coordination chemistry heralding the revival of perovskite compositions with pure DMSO, such as MAPbI 3 .

36 MATERIALS SCIENCE↗

DOE OSTI2023

Coordination Stoichiometry Effects on the Binding Hierarchy of Histamine and Imidazole–M 2+ Complexes

Histidine–M 2+ coordination bonds are a recognized bond motif in biogenic materials with high hardness and extensibility, which has led to growing interest in their use in soft materials for mechanical function. However, the effect of different metal ions on the stability of the coordination complex remains poorly understood, complicating their implementation in metal-coordinated polymer materials. Herein, rheology experiments and density functional theory calculations are used to characterize the stability of coordination complexes and establish the binding hierarchy of histamine and imidazole with Ni 2+ , Cu 2+ , and Zn 2+ . It is found that the binding hierarchy is driven by the specific affinity of the metal ions to different coordination states, which can be macroscopically tuned by changing the metal-to-ligand stoichiometry of the metal-coordinated network. These findings facilitate the rational selection of metal ions for optimizing the mechanical properties of metal-coordinated materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

The crystal and coordination chemistry of neptunium in all its oxidation states: An expanded structural hierarchy of neptunium compounds

We report structures of 388 neptunium-bearing crystal structures are sorted into an expanded structural hierarchy and examined. The majority of structures contain Np(V) (149), Np(VI) (99), or Np(IV) (91) whereas structures containing Np(II), Np(III), Np(VII), or more than one oxidation state are rare. Coordination geometry of Np(V) and Np(VI) compounds is dominated by the approximately linear neptunyl cation. Actinyl–actinyl interactions (AAIs) are most prevalent in Np(V) compounds and are observed in 48% of these extended structures. Prismatic coordination geometries are commonly observed in Np(IV) compounds. Np(III) organometallic complexes display a variety of coordination modes. Coordination chemistry of Np(VII) compounds is dominated by the tetra-oxido core. Updated average bond length values are provided for Np(IV), Np(V), Np(VI), and Np(VII) compounds and updated bond valence parameters for Np(IV) are reported. A graphical notation system for neptunyl structures coordinated by organic ligands was developed to facilitate discussion and identify similarities between neptunyl compounds coordinated by oxyanions and neptunyl compounds coordinated by organic ligands.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Spectroscopic characterization of Mn 2+ and Cd 2+ coordination to phosphorothioates in the conserved A9 metal site of the hammerhead ribozyme

Phosphorothioate modifications have widespread use in the field of nucleic acids. As substitution of sulfur for oxygen can alter metal coordination preferences, the phosphorothioate metal-rescue experiment is a powerful method for identifying metal coordination sites that influence specific properties in a large RNAs. The A9/G10.1 metal binding site of the hammerhead ribozyme (HHRz) has previously been shown to be functionally important through phosphorothioate rescue experiments. While an A9-S Rp substitution is inhibitory in Mg 2+ , thiophilic Cd 2+ rescues HHRz activity. Mn 2+ is also often used in phosphorothioate metal-rescue studies but does not support activity for the A9-S Rp HHRz. Here, we use EPR, electron spin-echo envelope modulation (ESEEM), and X-ray absorption spectroscopic methods to directly probe the structural consequences of Mn 2+ and Cd 2+ coordination to R p and S p phosphorothioate modifications at the A9/G10.1 site in the truncated hammerhead ribozyme (tHHRz). The results demonstrate that while Cd 2+ does indeed bind to S in the thio-substituted ligand, Mn 2+ coordinates to the non–sulfur oxo group of this phosphorothioate, regardless of isomer. Computational models demonstrate the energetic preference of Mn—O over Mn—S coordination in metal-dimethylthiophosphate models. In the case of the tHHRz, the resulting Mn 2+ coordination preference of oxygen in either R p or S p A9 phosphorothioates differentially tunes catalytic activity, with Mn—O coordination in the A9-S Rp phosphorothioate enzyme being inhibitory.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Coordination and control – limits in standard representations of multi-reservoir operations in hydrological modeling

Abstract. Major multi-reservoir cascades represent a primary mechanism for dealing with hydrologic variability and extremes within institutionally complex river basins worldwide. These coordinated management processes fundamentally reshape water balance dynamics. Yet, multi-reservoir coordination processes have been largely ignored in the increasingly sophisticated representations of reservoir operations within large-scale hydrological models. The aim of this paper is twofold, namely (i) to provide evidence that the common modeling practice of parameterizing each reservoir in a cascade independently from the others is a significant approximation and (ii) to demonstrate potential unintended consequences of this independence approximation when simulating the dynamics of hydrological extremes in complex reservoir cascades. We explore these questions using the Water Balance Model, which features detailed representations of the human infrastructure coupled to the natural processes that shape water balance dynamics. It is applied to the Upper Snake River basin in the western US and its heavily regulated multi-reservoir cascade. We employ a time-varying sensitivity analysis that utilizes the method of Morris factor screening to explicitly track how the dominant release rule parameters evolve both along the cascade and in time according to seasonal high- and low-flow events. This enables us to address aim (i) by demonstrating how the progressive and cumulative dominance of upstream releases significantly dampens the ability of downstream reservoir rules' parameters to influence flow conditions. We address aim (ii) by comparing simulation results with observed reservoir operations during critical low-flow and high-flow events in the basin. Our time-varying parameter sensitivity analysis with the method of Morris clarifies how independent single-reservoir parameterizations and their tacit assumption of independence leads to reservoir release behaviors that generate artificial water shortages and flooding, whereas the observed coordinated cascade operations avoided these outcomes for the same events. To further explore the role of (non-)coordination in the large deviations from the observed operations, we use an offline multi-reservoir water balance model in which adding basic coordination mechanisms drawn from the observed emergency operations is sufficient to correct the deficiencies of the independently parameterized reservoir rules from the hydrological model. These results demonstrate the importance of understanding the state–space context in which reservoir releases occur and where operational coordination plays a crucial role in avoiding or mitigating water-related extremes. Understanding how major infrastructure is coordinated and controlled in major river basins is essential for properly assessing future flood and drought hazards in a changing world.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1976

A space-time tensor formulation for continuum mechanics in general curvilinear, moving, and deforming coordinate systems

Tensor methods are used to express the continuum equations of motion in general curvilinear, moving, and deforming coordinate systems. The space-time tensor formulation is applicable to situations in which, for example, the boundaries move and deform. Placing a coordinate surface on such a boundary simplifies the boundary condition treatment. The space-time tensor formulation is also applicable to coordinate systems with coordinate surfaces defined as surfaces of constant pressure, density, temperature, or any other scalar continuum field function. The vanishing of the function gradient components along the coordinate surfaces may simplify the set of governing equations. In numerical integration of the equations of motion, the freedom of motion of the coordinate surfaces provides a potential for enhanced resolution of the continuum field function. An example problem of an incompressible, inviscid fluid with a top free surface is considered, where the surfaces of constant pressure (including the top free surface) are coordinate surfaces.

Avis, L. M.↗

NASA NTRS2022

Coordinating Innovative Technology Development at NASA

Innovation requires continually using and coordinating new knowledge on the current, anticipated, and even unanticipated developments in a given area. You do not want to simply repeat what others are doing, so you must remain aware of other activities in your area of interest. You also have to maintain awareness of where the cutting edge is, because the limit of what’s possible is continually pushed and redefined. Finally, “smart” innovation involves not only seeking innovative solutions to anticipated problems but also being prepared to respond to unanticipated problems or even unanticipated solutions. As the leading U.S. agency for aeronautics development, cutting-edge scientific discovery, and human space exploration, the National Aeronautics and Space Administration (NASA) must remain at the forefront of innovation. NASA enables innovation in technology development through a coordinated effort among its internal mission directorates and its partners in government, commercial, and academic sectors. As an independent office, NASA’s Office of Technology, Policy, and Strategy (OTPS) provides the coordination effort necessary to ensure innovation. OTPS uses and coordinates inputs from a broad community of experts. With these inputs, OTPS identifies and communicates shared needs and opportunities for partnership. OTPS provides strategic advice to synergize and ultimately facilitate innovative technology development both within and outside NASA. This paper summarizes NASA’s approach to ensuring innovation through a deliberately coordinated effort. In this paper, we first provide examples of how this coordination has enabled innovative technology development. We then describe how NASA’s mission directorates use input from a broad community of experts to inform innovative technology development. Finally, we describe OTPS’s role in coordinating inputs from both internal and external experts, including standardizing communication about technology developments, facilitating conversations with external partners on shared technology needs and solutions, and advising on strategies and policies to ensure innovative technology development. This paper can help members of the aerospace community understand their role in NASA’s innovation efforts and how to engage OTPS in conversations about potential partnership.

Erica Rodgers↗

NASA NTRSDate not supplied

Coordinating Innovative Technology Development at NASA

Innovation requires continually using and coordinating new knowledge on the current, anticipated, and even unanticipated developments in a given area. You do not want to simply repeat what others are doing, so you must remain aware of other activities in your area of interest. You also have to maintain awareness of where the cutting edge is, because the limit of what’s possible is continually pushed and redefined. Finally, “smart” innovation involves not only seeking innovative solutions to anticipated problems but also being prepared to respond to unanticipated problems or even unanticipated solutions. As the leading U.S. agency for aeronautics development, cutting-edge scientific discovery, and human space exploration, the National Aeronautics and Space Administration (NASA) must remain at the forefront of innovation. NASA enables innovation in technology development through a coordinated effort among its internal mission directorates and its partners in government, commercial, and academic sectors. As an independent office, NASA’s Office of Technology, Policy, and Strategy (OTPS) provides the coordination effort necessary to ensure innovation. OTPS uses and coordinates inputs from a broad community of experts. With these inputs, OTPS identifies and communicates shared needs and opportunities for partnership. OTPS provides strategic advice to synergize and ultimately facilitate innovative technology development both within and outside NASA. This paper summarizes NASA’s approach to ensuring innovation through a deliberately coordinated effort. In this paper, we first provide examples of how this coordination has enabled innovative technology development. We then describe how NASA’s mission directorates use input from a broad community of experts to inform innovative technology development. Finally, we describe OTPS’s role in coordinating inputs from both internal and external experts, including standardizing communication about technology developments, facilitating conversations with external partners on shared technology needs and solutions, and advising on strategies and policies to ensure innovative technology development. This paper can help members of the aerospace community understand their role in NASA’s innovation efforts and how to engage OTPS in conversations about potential partnership.

Erica Rodgers↗

NASA NTRSDate not supplied

Coordinating Innovative Technology Development at NASA

Innovation requires continually using and coordinating new knowledge on the current, anticipated, and even unanticipated developments in a given area. You do not want to simply repeat what others are doing, so you must remain aware of other activities in your area of interest. You also have to maintain awareness of where the cutting edge is, because the limit of what’s possible is continually pushed and redefined. Finally, “smart” innovation involves not only seeking innovative solutions to anticipated problems but also being prepared to respond to unanticipated problems or even unanticipated solutions. As the leading U.S. agency for aeronautics development, cutting-edge scientific discovery, and human space exploration, the National Aeronautics and Space Administration (NASA) must remain at the forefront of innovation. NASA enables innovation in technology development through a coordinated effort among its internal mission directorates and its partners in government, commercial, and academic sectors. As an independent office, NASA’s Office of Technology, Policy, and Strategy (OTPS) provides the coordination effort necessary to ensure innovation. OTPS uses and coordinates inputs from a broad community of experts. With these inputs, OTPS identifies and communicates shared needs and opportunities for partnership. OTPS provides strategic advice to synergize and ultimately facilitate innovative technology development both within and outside NASA. This paper summarizes NASA’s approach to ensuring innovation through a deliberately coordinated effort. In this paper, we first provide examples of how this coordination has enabled innovative technology development. We then describe how NASA’s mission directorates use input from a broad community of experts to inform innovative technology development. Finally, we describe OTPS’s role in coordinating inputs from both internal and external experts, including standardizing communication about technology developments, facilitating conversations with external partners on shared technology needs and solutions, and advising on strategies and policies to ensure innovative technology development. This paper can help members of the aerospace community understand their role in NASA’s innovation efforts and how to engage OTPS in conversations about potential partnership.

Erica Rodgers↗

DOE OSTI2021

GT Flex: A Coordinated Multi-Building Pilot Study

Buildings are a significant and untapped resource for providing utility electric grid services. Recent studies have estimated that buildings could reduce the peak demand on the electric grid in the U.S. by almost 25% through effective combinations of energy efficiency (EE) measures and load flexibility strategies (Langevin et al. 2021). The U.S. Department of Energy (DOE) has established a goal to triple energy efficiency and demand flexibility in both residential and commercial sections by 2030 compared to 2020 levels (Satchwell et al. 2021). Such findings place buildings alongside electric vehicles, photovoltaics, electric batteries, and other distributed energy resources (DERs) as primary technologies needed for supporting high renewable energy generation grids. Coordinating and optimizing multiple buildings and other DERs is more beneficial and valuable when compared with individual buildings and DERs operating as siloed resources, uncoordinated with others (Olgyay et al. 2020). A pilot study at the Georgia Institute of Technology (GIT) was conducted to evaluate value propositions of a multi-building scale project seeking carbon reduction, energy efficiency and grid-interactive capabilities, by demonstrating the means by which stakeholders can determine the technical and financial merits of grid-interactivity and energy efficiency technologies coordinated across multiple assets. The study focused on analyzing technical feasibility of deploying thermal load flexibility strategies at the multi-building scale, coordinated to not exceed existing infrastructure constraints at the pilot site. Results show that campus can provide 3-3.5 MW of potential load shed over a 4-hour event window through coordinated dispatch of thermal cooling load flexibility without exceeding existing infrastructure capacities. Under future high renewable scenarios, this thermal flexibility resource is also valuable when coordinated to reduce curtailment of intermittent renewables. Economic analyses were performed to effectively communicate various value propositions of grid-interactive and efficient building (GEB) thermal flexibility strategies. Load flexibility presents a financial value proposition to the campus today. By conducting rationalized, coordinated dispatch in response to real time price (RTP) fluctuations, the campus can benefit materially from daily price arbitrage. The RTP signal acts as an aggregating mechanism between the utility and customer to call on demand flexibility resources, with a large portion of the benefit deriving from a relatively small number of days. Realizing and maximizing this benefit with thermal load flexibility requires careful attention to the timing of pricing signals and parameterization of dispatch to overcome efficiency penalties. Grid value and signals are expected to evolve over time, and thermal load flexibility shows potential to adapt dispatch logic to support intermittent renewable generation.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

NASA NTRS2015

Coordinate Families for the Schwarzschild Geometry Based on Radial Timelike Geodesics

We explore the connections between various coordinate systems associated with observers moving inwardly along radial geodesics in the Schwarzschild geometry. Painleve-Gullstrand (PG) time is adapted to freely falling observers dropped from rest from in nity; Lake-Martel-Poisson (LMP) time coordinates are adapted to observers who start at in nity with non-zero initial inward velocity; Gautreau-Ho mann (GH) time coordinates are adapted to observers dropped from rest from a nite distance from the black hole horizon. We construct from these an LMP family and a propertime family of time coordinates, the intersection of which is PG time. We demonstrate that these coordinate families are distinct, but related, one-parameter generalizations of PG time, and show linkage to Lema^tre coordinates as well.

start at infinity with non-zero initial inward vel↗

NASA NTRS2015

Coordinate Families for the Schwarzschild Geometry Based on Radial Timelike Geodesics

We explore the connections between various coordinate systems associated with observersmoving inwardly along radial geodesics in the Schwarzschild geometry. Painleve-Gullstrand (PG) time is adapted to freely falling observers dropped from rest from infinity; Lake-Martel-Poisson (LMP) time coordinates are adapted to observers who start at infinity with non-zero initial inward velocity; Gautreau-Hoffmann time coordinates are adapted to observers dropped from rest from a finite distance from the black hole horizon.We construct from these an LMP family and a proper-time family of time coordinates, the intersection of which is PG time. We demonstrate that these coordinate families are distinct, but related, one-parameter generalizations of PG time, and show linkage to Lemaître coordinates as well.

Schwarzschild geometry↗

DOE OSTI2021

Tonal Emergence: An agent-based model of tonal coordination

Humans have a remarkable capacity for coordination. Our ability to interact and act jointly in groups is crucial to our success as a species. Joint Action (JA) research has often concerned itself with simplistic behaviors in highly constrained laboratory tasks. But there has been a growing interest in understanding complex coordination in more open-ended contexts. In this regard, collective music improvisation has emerged as a fascinating model domain for studying basic JA mechanisms in an unconstrained and highly sophisticated setting. A number of empirical studies have begun to elucidate coordination mechanisms underlying joint musical improvisation, but these empirical findings have yet to be cached out in a working computational model. The present work fills this gap by presenting TonalEmergence, an idealized agent-based model of improvised musical coordination. TonalEmergence models the coordination of notes played by improvisers to generate harmony (i.e., tonality), by simulating agents that stochastically generate notes biased towards maximizing harmonic consonance given their partner’s previous notes. Here, the model replicates an interesting empirical result from a previous study of professional jazz pianists: feedback loops of mutual adaptation between interacting agents support the production of consonant harmony. The model is further explored to show how complex tonal dynamics, such as the production and dissolution of stable tonal centers, are supported by agents that are characterized by (i) a tendency to strive toward consonance, (ii) stochasticity, and (iii) a limited memory for previously played notes. TonalEmergence thus provides a grounded computational model to simulate and probe the coordination mechanisms underpinning one of the more remarkable feats of human cognition: collective music improvisation.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2024

Plutonium and Cerium Perrhenate/Pertechnetate Coordination Polymers and Frameworks

Spent nuclear fuel (SNF) contains transuranic and lanthanide species, which are sometimes recovered and repurposed. One particularly problematic fission product, 99 TcO 4 – , hampers this recovery via coextraction with high valence metals, perhaps by complexation during aqueous reprocessing of SNF. There is limited molecular-level knowledge concerning the coordination chemistry between TcO 4 – or its well-known surrogate ReO 4 – and transuranic/lanthanide species. In the current study, we investigated the coordination of ReO 4 – /TcO 4 – with plutonium and cerium cations by structural and chemical characterization of a series of isolated extended solids. In this study, Ce represents both trivalent lanthanides and is considered a surrogate for Pu, respectively, in its common trivalent and tetravalent oxidation states. The structural elucidation of the seven isolated crystalline solids revealed that ReO 4 – /TcO 4 – directly connects to Pu IV , Pu VI O 2 2 + , Ce III , and Ce IV in the terminal and bridging coordination modes, leading to 1-, 2-, and 3-dimensional frameworks. For example, ReO 4 – coordination to Pu(IV) formed a 1D chain or 2D framework, isostructural with previously isolated Th(IV) compounds. However, Pu VI O 2 2 + alternating with ReO 4 – led to a unique 1D chain, different from the prior-reported U(VI)/Np(VI)-ReO 4 – /TcO 4 – structures. Coordination of ReO 4 – /TcO 4 – with Ce(III) promotes the assembly of 3D frameworks. Finally, attempted synthesis of a Ce(IV)-ReO 4 – compound resulted in a 2D framework with a mixed-valence Ce III/IV . The highly acidic reaction conditions supported the reduction of both Ce IV and Tc VII , challenging isolation of compounds featuring these species. Only one TcO 4 -containing structure was obtained in this study (Ce III –TcO 4 3D framework), vs the six total Ce/Pu-ReO 4 compounds. Furthermore, our three Pu-ReO 4 crystal structures are the first reported and translated to atomic-level information about Pu-TcO 4 coordination in nuclear fuel reprocessing scenarios, in addition to broadening our knowledge of bonding trends in the early, high-valence actinides.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2024

Influence of Aqueous Phase Acidity on Ln(III) Coordination by N , N , N ', N '-Tetraoctyldiglycolamide

Here, this study highlights the importance of combining distribution ratio measurements with multiple spectroscopic techniques to provide a more comprehensive understanding of organic phase Ln coordination chemistry. Solvent extraction investigations with N,N,N',N'-tetraoctyldiglycolamide (TODGA) in n-heptane reveal the sensitivity of Ln complexation to the HNO 3 concentration. Distribution ratio measurements in tandem with UV–Vis demonstrated that increasing the concentration of HNO3 above 0.5 M with a constant NO 3 – of 1 M increases the number of coordinating TODGA molecules, from a 1:2 to a 1:3 Ln:TODGA complex. At each concentration of HNO 3 considered herein (from 0.01 to 1 M), Eu lifetime analysis demonstrated no evidence of H 2 O coordination. Results from Fourier transform infrared investigations suggest the presence of inner-sphere NO 3 – under low concentrations of HNO 3 when the 1:2 Ln:TODGA complex is present. Increasing the HNO 3 concentration above 0.5 M increases the propensity for outer-sphere interactions by removing the coordinated NO 3 – and saturating the Ln coordination sphere with three TODGA molecules, resulting in the well-established cationic, trischelate homoleptic [Ln(TODGA) 3 ] 3+ complex. This work demonstrates the importance in considering the NO 3 – source for solvent extraction systems. In particular, for systems with an affinity for outer-sphere interactions with molar concentrations of HNO 3 , changing the NO 3 – source can change the inner-sphere coordination of the Ln complex, which, in turn, affects the separation efficacy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Characterization of Uranyl Coordinated by Equatorial Oxygen: Oxo in UO 3 versus Oxyl in UO 3 +

Uranium trioxide, UO 3 , has a T-shaped structure with bent uranyl, UO 2 2+ , coordinated by an equatorial oxo, O 2– . The structure of cation UO 3 + is similar but with an equatorial oxyl, O •– . Neutral and cationic uranium trioxide coordinated by nitrates were characterized by collision induced dissociation (CID), infrared multiple-photon dissociation (IRMPD) spectroscopy, and density functional theory. CID of uranyl nitrate, [UO 2 (NO 3 ) 3 ] – (complex A1), eliminates NO 2 to produce nitrate-coordinated UO 3 + , [UO 2 (O • )(NO 3 ) 2 ]– (B1), which ejects NO 3 to yield UO 3 in [UO 2 (O)(NO 3 )] – (C1). Finally, C1 associates with H 2 O to afford uranyl hydroxide in [UO 2 (OH) 2 (NO 3 )] – (D1). IRMPD of B1, C1, and D1 confirms uranyl equatorially coordinated by nitrate(s) along with the following ligands: (B1) radical oxyl O •– ; (C1) oxo O 2– ; and (D1) two hydroxyls, OH – . As the nitrates are bidentate, the equatorial coordination is six in A1, five in B1, four in D1, and three in C1. Ligand congestion in low-coordinate C1 suggests orbital-directed bonding. Hydrolysis of the equatorial oxo in C1 epitomizes the inverse trans influence in UO 3 , which is uranyl with inert axial oxos and a reactive equatorial oxo. The uranyl ν 3 IR frequencies indicate the following donor ordering: O 2– [best donor] >> O •– > OH – > NO 3 – .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Sulfur-Donor Solvents Strongly Coordinate Pb 2+ in Hybrid Organic–Inorganic Perovskite Precursor Solutions

Strong coordination between Lewis-basic processing additives and the Lewis-acidic lead halide in hybrid organic–inorganic perovskite (HOIP) precursor solutions is required to solubilize the lead halide, and subsequently access the appropriate crystallization kinetics and attain the desired morphology of perovskite active layers. While oxygen-donor solvents and additives, such as dimethylformamide and dimethyl sulfoxide, are widely used for perovskite processing, we demonstrate here that “soft” sulfur-donor solvents exhibit stronger coordination to the “borderline soft” Lewis acid Pb 2+ center of PbI 2 relative to “hard” O-donor solvents in the precursor solution. The stronger coordination of S-donor solvents compared to O-donor solvents to Pb 2+ implies that such compounds can be useful additives to HOIP precursor solutions. Density-functional calculations of the enthalpy change resulting from the coordination of solvents to Pb 2+ provide direct numerical comparison of the strength of O-donor and S-donor coordination with Pb 2+ and expands the library of candidate S-donor compounds. Our results provide a roadmap for processing additive selection and expand the previously limited choice of perovskite processing additives to include strongly coordinating S-donor compounds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗