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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Ligand-Induced Size-Dependent Circular Dichroism in Quantum Dots

Recent experiments have probed the chiral properties of semiconductor nanocrystal (NC) quantum dots (QDs), but understanding the circular dichroism line shape, excitonic features, and chirality induction mechanism remains a challenge. We propose an atomistic pseudopotential method to model chiral ligand passivated QDs, computing circular dichroism (CD) spectra for CdSe QDs (2.6-3.8 nm). We find strong agreement between calculated and measured line shapes, predicting consistent bisignate line shapes with decreasing CD magnitude as size increases. Further, our analysis reveals the origin of bisignate line shapes, arising from nondegenerate excitons with opposing angular momenta. We also explore the impact of chiral ligand orientation on QD surfaces, observing changes in the optical activity magnitude and sign. This orientation sensitivity offers the means to distinguish ordered from disordered ligand configurations, facilitating the study of order-disorder transitions at ligand-QD interfaces.

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

Bidentate Ligand-Induced Oriented Transformation of CsPbBr 3 Perovskite Nanocrystals into Nanowires for X-ray Photodetectors

We report shape and dimensionality control by ligands is an efficient way to fabricate high-quality perovskite nanocrystals (NCs) with optoelectronic properties. Herein, to realize oriented transformations between different morphologies of CsPbBr 3 nanocrystals, we conceived of the use of defects and bidentate ligands to synergistically drive the reorientation of CsPbBr3nanocrystals into CsPbBr 3 nanowires (NWs). By employing aminocaproic acid as the bidentate ligand, CsPbBr 3 NWs were reconstructed from the CsPbBr 3 NCs (~7 nm) with 20-60 nm in width and several micrometers in length, as well as a 527 nm photoluminescence (PL) peak, 59% PL quantum yield, and 98.5 ns PL lifetime. The bidentate ligand-directed anisotropic shape evolution and growth of perovskite NWs from NCs was elucidated by transmission electronmicroscopy and PL studies. The photodetectors fabricated with the reconstructed CsPbBr 3 NWs displayed a photocurrent enhancement (2.75 × 10 -11 A) compared with that of the devices based on solution-synthesized NWs (2.28 × 10 -11 A). The device also showed a short response time, indicating its more sensitive photoelectric response. This process provides a viable approach to engineering diverse morphologies of perovskite nanocrystals for optoelectronic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Catalytic Hydrogenation of a Ruthenium Carbonyl to Formyl Enabled by Metal–Ligand Cooperation

Metal formyl complexes are critical intermediates in the reduction of CO to valuable products such as methanol and higher alcohols/hydrocarbons, yet examples of formyl generation via the catalytic hydrogenation of transition metal carbonyl complexes under mild conditions are lacking. The catalytic hydrogenation of a ruthenium carbonyl complex with H 2 to produce a formyl complex is reported here. Two classes of hydrogenation catalysts were compared: bis(diphosphine)-ligated complexes that proceed via termolecular H 2 splitting with an external base and pincer-ligated complexes that proceed via an H 2 splitting mechanism involving metal–ligand cooperativity. The hydride transfer and H 2 splitting steps were evaluated for both classes of catalysts, revealing advantages for catalysts that utilize metal–ligand cooperativity and elucidating conditions to promote formyl generation. Only the pincer-ligated Ir and Ru complexes capable of reacting via pathways involving metal–ligand cooperativity were suitable for catalysis. Using 1–10 mol % of the catalysts (PNP)Ir(H) 2 and (HPNP)Ru(H) 2 (CO) (PNP = ( i Pr 2 PC 2 H 4 ) 2 N – ), which use metal–ligand cooperation to activate H 2 , up to 10 turnovers or up to 71% yield were achieved for the conversion of [Ru(bpy) 2 (CO) 2 ] 2+ (bpy = 2,2′-bipyridine) to the formyl complex [Ru(bpy) 2 (CO)(CHO)] + . The Lewis acid B(C 6 F 5 ) 3 was required as an additive to achieve high yields of the formyl complex using (HPNP)Ru(H) 2 (CO) as a catalyst. In conclusion, the catalytic route avoids the use of expensive stoichiometric reagents, such as borohydride, instead generating metal formyls that are key intermediates in CO reduction schemes with H 2 gas.

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

Amine-Assisted Ligand-Exchange Method to Enhance Photovoltaic Parameters in FAPbI3 Nanocrystal Solar Cells

Perovskite colloidal nanocrystals (PeNCs) have exceptional optoelectronic properties and phase stability, making them promising for photovoltaic applications. However, insulating ligands on PeNC surfaces limit the current density and reduce the power conversion efficiency (PCE) in PeNC solar cells (SCs). This study introduces an amine-assisted ligand-exchange (ALE) strategy using 3-phenyl-1-propylamine (3P1P) to effectively remove long ligands from PeNC films. ALE reduced long-chain ligand density without increasing the number of defect states and therefore reduced the exciton-binding energy of FAPbI3 NC films. These changes facilitated exciton dissociation and charge transport in FAPbI3 PeNC SCs. The facilitation of exciton dissociation was due to the increased magnetic dipole interaction between excitons after the ALE process. The use of ALE achieved FAPbI3 PeNC SCs that had an improved short-circuit current density of 17.98 mA/cm2 and a PCE of 15.56% with improved stability after the treatment and negligible hysteresis. This work provides new insight into engineering PeNC films.

amines↗
DOE OSTI2025

Ligand-Functionalized Polymer Membranes for Selective Ion Separations

Selective ion separations are central to technologies spanning water purification, resource recovery, and clean energy. Conventional polymer membranes, which rely on steric hindrance or Donnan exclusion, struggle to discriminate between chemically similar ions in high-ionic-strength environments. Ligand-functionalized membranes offer a transformative strategy by embedding molecular recognition directly into polymer matrices, enabling selective complexation and transport. Here, this Viewpoint highlights the structure–function relationships underlying ligand-mediated ion separation, emphasizing the interplay of dehydration penalties, ligand coordination, and nanoscale confinement. We discuss design principles, denticity, donor identity, rigidity, and spatial organization, alongside the permeability–selectivity trade-off, multicomponent effects, and stability challenges. Finally, we outline emerging strategies, from bioinspired ligands to computationally guided design, that chart a path toward next-generation membranes for precise and energy-efficient ion separations.

ions↗
DOE OSTI2022

Isolation of a Cu–H Monomer Enabled by Remote Steric Substitution of a N-Heterocyclic Carbene Ligand: Stoichiometric Insertion and Catalytic Hydroboration of Internal Alkenes

Transient Cu–H monomers have long been invoked in the mechanisms of substrate insertion in Cu–H catalysis. Their role from Cu–H aggregates has been mostly inferred since ligands to stabilize these monomeric intermediates for systematic studies remain limited. Within the last decade, new sterically demanding N-heterocyclic carbene (NHC) ligands have led to isolable Cu–H dimers and, in some cases, spectroscopic characterization of Cu–H monomers in solution. In this work, we report an NHC ligand, IPr*R, containing para R groups of CHPh 2 and CPh 3 on the ligand periphery for the isolation of a Cu–H monomer for insertion of internal alkenes. This reactivity has not been reported for (NHC)CuH complexes despite their common application in Cu–H-catalyzed hydrofunctionalization. Changing from CHPh 2 to CPh 3 impacts the relative concentration of Cu–H monomers, rate of alkene insertion, and reaction of a trisubstituted internal alkene. Specifically, for R = CPh 3 , monomeric (IPr*CPh 3 )CuH was isolated and provided >95% monomer (10 mM in C 6 D 6 ). In contrast, for R = CHPh 2 , solutions of [(IPr*CHPh 2 )CuH] 2 are 80% dimer and 20% (IPr*CHPh 2 )CuH monomer at 25 °C based on 1 H, 13 C, and 1 H– 13 C HMBC NMR spectroscopy. Quantitative 1 H NMR kinetic studies on cyclopentene insertion into Cu–H complexes to form the corresponding Cu–cyclopentyl complexes demonstrate a strong dependence on the rate of insertion and concentration of the Cu–H monomer. Only (IPr*CPh 3 )CuH, which has a high monomer concentration, underwent regioselective insertion of a trisubstituted internal alkene, 1-methylcyclopentene, to give (IPr*CPh 3 )Cu(2-methylcyclopentyl), which has been crystallographically characterized. We also demonstrated that (IPr*CPh 3 )CuH catalyzes the hydroboration of cyclopentene and methylcyclopentene with pinacolborane.

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

Ligand Desorption and Fragmentation in Oleate-Capped CdSe Nanocrystals under High-Intensity Photoexcitation

Semiconductor nanocrystals (NCs) offer prospective use as active optical elements in photovoltaics, light-emitting diodes, lasers, and photocatalysts due to their tunable optical absorption and emission properties, high stability, and scalable solution processing, as well as compatibility with additive manufacturing routes. Over the course of experiments, during device fabrication, or while in use commercially, these materials are often subjected to intense or prolonged electronic excitation and high carrier densities. The influence of such conditions on ligand integrity and binding remains underexplored. Here, in this study, we expose CdSe NCs to laser excitation and monitor changes in oleate that is covalently attached to the NC surface using nuclear magnetic resonance as a function of time and laser intensity. Higher photon doses cause increased rates of ligand loss from the particles, with upward of 50% total ligand desorption measured for the longest, most intense excitation. Surprisingly, for a range of excitation intensities, fragmentation of the oleate is detected and occurs concomitantly with formation of aldehydes, terminal alkenes, H 2 , and water. After illumination, NC size, shape, and bandgap remain constant although low-energy absorption features (Urbach tails) develop in some samples, indicating formation of substantial trap states. The observed reaction chemistry, which here occurs with low photon to chemical conversion efficiency, suggests that ligand reactivity may require examination for improved NC dispersion stability but can also be manipulated to yield desired photocatalytically accessed chemical species.

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

Bidentate Lewis Base Ligand-Mediated Surface Stabilization and Modulation of the Electronic Structure of CsPbBr 3 Perovskite Nanocrystals

The desorption of conventional ligands from the surface of halide perovskite nanocrystals (NCs) often causes their structural instability and the deterioration of the optoelectronic properties. To address this challenge, we present an approach of using a bidentate Lewis base ligand, namely, 1,4-bis(diphenylphosphino)butane (DBPP), for the synthesis of CsPbBr 3 NCs. The phosphine group of DBPP has a strong interaction with PbBr 2 precursor, forming a highly crystalline intermediate complex during the reaction. In the presence of oleic acid, the uncoordinated phosphine group of DBPP is converted into the phosphonium cation, which strongly binds with the surface bromide of the formed CsPbBr 3 NCs through hydrogen bonding. Density functional theory calculations suggest that DBPP can strongly bind to the undercoordinated lead and surface bromide ions of CsPbBr 3 NCs through its unprotonated and protonated phosphine groups, respectively. The robust binding of DBPP with the surface of perovskite NCs helps to preserve their structural integrity under various environmental stresses. Moreover, the electron density and energy levels are regulated in DBPP-capped CsPbBr 3 NCs via the efficient transfer of electrons from the ligands to the NCs, resulting in their improved photocatalytic CO 2 reduction performance. Furthermore, our study highlights the potential of using bidentate ligands to stabilize the surface of perovskite NCs and modulate their optical and electronic properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Pursuing Heteroleptic Ligand Design Principles for Photoactive Fe Complexes with Ultrafast X-ray Emission and Variable-Temperature Optical Spectroscopies

Understanding the key parameters that govern the photophysical and photochemical properties of transition metal complexes is essential for the development of efficient photosensitizers for photocatalytic applications. Achieving this objective necessitates clear and detailed investigations of their electronic excited states, for which time-resolved metal Kβ X-ray emission spectroscopy (XES) has proven highly effective. Here, we present a time-resolved Fe Kβ XES study of a heteroleptic Fe(II) polypyridyl carbene complex, [Fe(phen) 2 (C 4 H 10 N 4 )] 2+ (1; phen = 1,10-phenanthroline), utilizing both the valence-to-core and Kβ mainline spectral regions, complemented by variable-temperature transient optical absorption (VT-TA) spectroscopy. Detailed analysis of the time-resolved Kβ XES data, supported by density functional theory (DFT) calculations and an Eyring analysis of the VT-TA data, reveals parallel excited state relaxation dynamics that support an assignment of the long-lived excited state to a triplet metal-centered state. Placing these results in the context of prior studies of heteroleptic Fe(II) polypyridyl cyanide complexes motivated a series of DFT calculations to investigate the effects of ligand structural flexibility and arrangement. These calculations reinforce the experimentally derived conclusion that constraining structural flexibility with multidentate ligands significantly impacts the excited state relaxation dynamics. Furthermore, our study emphasizes that the arrangement of strong field ligands in heteroleptic complexes substantially affects the energy of Jahn–Teller active triplet metal-centered states in low-spin d 6 metal complexes. Together, these findings provide synthetic design principles for extending metal-to-ligand charge transfer excited state lifetimes of heteroleptic Fe complexes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Coupled Hydrothermal Extraction and Ligand-Associated Swellable Glass Media Recovery of Rare Earth Elements from Coal Fly Ash (Final Report)

Wayne State University (WSU) researchers, in collaboration with the University of California-Los Angeles (UCLA) and Los Alamos National Laboratory (LANL), have successfully developed a new sorbent media used in a process that concentrated the rare earth content in a coal fly ash sample from southeast MI by >350×, resulting in >13 wt% REO powder. The project developed a new DTPA-associated media that was used to concentrate total REEs. This project demonstrated a coupled hydrothermal extraction and solid-liquid recovery process that produced REO powder from raw fly ash while nearly eliminating the use of organic solvents. The project successfully: 1) identified a commercially viable ash supply with >$2.5 M in REO value being deposited monthly, 2) hydrothermally extracted >77% of REEs in coal fly ash (20% more than acid alone), 3) developed a new sorbent media that was used to concentrate REEs, 4) and engineered a process that resulted in a >13 wt% REO powder. The media also demonstrates a selectivity for mid and heavy REEs over Ce and La and the potential for use in separating individual rare earth elements. An invention disclosure for the sorbent media has been filed with WSU and a patent application will be submitted in the near future. The project examined the potential to couple hydrothermal leaching of coal fly ash with the engineering of a custom ligand-associated media to provide an organic solvent-free method of extracting and recovering REEs. Fly ash feedstock was collected from Detroit area coal-fired power plants, characterized for REE content, and subjected to a bench-top batch hydrothermal leaching/dissolution process inside custom-build pressure reactors at Los Alamos National Laboratory (LANL). This process applied a dissolution technique previously developed to process spent nuclear fuel and other nuclear materials. The modified ash was acidified and the resulting leachate was enriched with REEs along with Ca, Al, and Si. Ligands known to be effective in lanthanide/actinide separation were evaluated based on a series of criteria such as selectivity and association to organosilica through hydrophobicity. Batch experiments were conducted to establish the best conditions (e.g., pH, eluent, etc.) and best ligand systems for the effective extraction of REEs from the alkaline feed solution obtained from the hydrothermal leaching process. Once the organosilica-ligand extraction media was developed for REE concentration, an acidic solution was used to back extract and concentrate the REEs into a heavily REE-laden strip solution. The REEs in the strip solution were precipitated with oxalate to produce rare earth oxides.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2023

Ligand Tuning in Cu(pyalk)2 Water Oxidation Electrocatalysis

Molecular copper water oxidation electrocatalysts have been extensively studied in recent years for their potential use in artificial photosynthetic systems for solar energy conversion. Although ligand modification and its ability to influence catalytic properties is a key advantage of molecular systems, there are, as yet, few examples of systematic studies of these effects. Our oxidatively resistant pyalk (2-pyridyl-2-propanoate) ligand forms a complex with copper(II) that catalyzes water oxidation and provides an attractive scaffold for systematic ligand tuning. Here, we report a series of analogous copper complexes with electron-donating (methoxy-) and -withdrawing (methoxycarbonyl-) groups at the para-position of the pyalk ligand. Trends in the pKa and redox potential align with first-principles predictions for the electron-withdrawing and electron-donating groups. While the modified complexes show good activity for water oxidation, lowered faradaic efficiency in comparison to the parent complex highlights the importance of stability considerations for catalyst tuning.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Impact of the Electronic Properties of Chalcogenide Ligands in their Complexation with Uranyl Nitrate Complexes

The idea of covalency being directly correlated with selectivity in f-element separations has gained attention over the years. However, “covalency” as a concept is still under debate as it is not an experimental nor quantum mechanical observable. Regardless, covalency along with ionicity are still the main concepts used to explain the nature of the chemical bond of coordination complexes. Another concept that has gained the attention in the separations community is the hard-soft acid-base (HSAB) theory, which favors soft-donor ligands having the potential to increase selectivity for actinides (An) over the lanthanides (Ln) due to their ability to engage more effectively f-electrons in covalent interactions. However, it has been shown that while using softer donor ligands in fact increased orbital mixing and covalency with the actinides, it compromises the strength of the interaction owing to a decrease in the metal-ligand electrostatic interactions.1 Herein, we study the electronic structure of different types of chalcogenide ligands (LE, E = O, S, Se), their interaction with the uranyl ion, and their complexation free energies. Surprisingly, contrary to the expected order of covalency, i.e. An–LSe > An–LS > An–LO, our results suggest that the degree of covalency and associated complexation free energies depend on the nature of the coordinating moiety rather than solely on the directly coordinated atom. 1) Sadhu, Biswajit, and Michael Dolg. Enhancing actinide (III) over lanthanide (III) selectivity through hard-by-soft donor substitution: exploitation and implication of near-degeneracy-driven covalency. Inorganic Chemistry, 2019, 58, 9738 – 9748.

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

Stable Cuprous Hydroxide Nanostructures by Organic Ligand Functionalization

Abstract Copper compounds have been extensively investigated for diverse applications. However, studies of cuprous hydroxide (CuOH) have been scarce due to structural metastability. Herein, a facile, wet‐chemistry procedure is reported for the preparation of stable CuOH nanostructures via deliberate functionalization with select organic ligands, such as acetylene and mercapto derivatives. The resulting nanostructures are found to exhibit a nanoribbon morphology consisting of small nanocrystals embedded within a largely amorphous nanosheet‐like scaffold. The acetylene derivatives are found to anchor onto the CuOH forming CuC linkages, whereas CuS interfacial bonds are formed with the mercapto ligands. Effective electronic coupling occurs at the ligand‐core interface in the former, in contrast to mostly non‐conjugated interfacial bonds in the latter, as manifested in spectroscopic measurements and confirmed in theoretical studies based on first principles calculations. Notably, the acetylene‐capped CuOH nanostructures exhibit markedly enhanced photodynamic activity in the inhibition of bacteria growth, as compared to the mercapto‐capped counterparts due to a reduced material bandgap and effective photocatalytic generation of reactive oxygen species. Results from this study demonstrate that deliberate structural engineering with select organic ligands is an effective strategy in the stabilization and functionalization of CuOH nanostructures, a critical first step in exploring their diverse applications.

Liu, Qiming↗
DOE OSTI2024

Colloidal InAs Quantum Dot-Based Infrared Optoelectronics Enabled by Universal Dual-Ligand Passivation

Solution-processed low-bandgap semiconductors are crucial to next-generation infrared (IR) detection for various applications, such as autonomous driving, virtual reality, recognitions, and quantum communications. In particular, III–V group colloidal quantum dots (CQDs) are interesting as nontoxic bandgap-tunable materials and suitable for IR absorbers; however, the device performance is still lower than that of Pb-based devices. Herein, a universal surface-passivation method of InAs CQDs enabled by intermediate phase transfer (IPT), a preliminary process that exchanges native ligands with aromatic ligands on the CQD surface is presented. IPT yields highly stable CQD ink. In particular, desirable surface ligands with various reactivities can be obtained by dispersing them in green solvents. Furthermore, CQD near-infrared (NIR) photodetectors are demonstrated using solution processes. Careful surface ligand control via IPT is revealed that enables the modulation of surface-mediated photomultiplication, resulting in a notable gain control up to ≈10 with a fast rise/fall response time (≈12/36 ns). Considering the figure of merit (FOM), EQE versus response time (or –3 dB bandwidth), the optimal CQD photodiode yields one of the highest FOMs among all previously reported solution-processed nontoxic semiconductors comprising organics, perovskites, and CQDs in the NIR wavelength range.

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

Multiple Roles of Alkanethiolate‐Ligands in Direct Formation of H 2 O 2 over Pd Nanoparticles

Abstract Coadsorbed organic species including thiolates can promote direct synthesis of hydrogen peroxide from H 2 and O 2 over Pd particles. Here, density functional theory based kinetic modeling, augmented with activity measurements and vibrational spectroscopy are used to provide atomistic understanding of direct H 2 O 2 formation over alkylthiolate(RS) Pd. We find that the RS species are oxidized during reaction conditions yielding RSO 2 as the effective ligand. The RSO 2 ligand shows superior ability for proton transfer to the intermediate surface species OOH, which accelerates the formation of H 2 O 2 . The ligands promote the selectivity also by blocking sites for unselective water formation and by modifying the electronic structure of Pd. The work rationalizes observations of enhanced selectivity of direct H 2 O 2 formation over ligand‐funtionalized Pd nanoparticles and shows that engineering of organic surface modifiers can be used to promote desired hydrogen transfer routes.

Chen, Lin↗
DOE OSTI2022

Copper Complexes with Diazoolefin Ligands and their Photochemical Conversion into Alkenylidene Complexes

Abstract Homometallic copper complexes with alkenylidene ligands are discussed as intermediates in catalysis but the isolation of such complexes has remained elusive. Herein, we report the structural characterization of copper complexes with bridging and terminal alkenylidene ligands. The compounds were obtained by irradiation of Cu I complexes with N‐heterocyclic diazoolefin ligands. The complex with a terminal alkenylidene ligand required isolation in a crystalline matrix, and its structural characterization was enabled by in crystallo photolysis at low temperature.

Kooij, Bastiaan↗
DOE OSTI2022

Multiple Roles of Alkanethiolate‐Ligands in Direct Formation of H 2 O 2 over Pd Nanoparticles

Abstract Coadsorbed organic species including thiolates can promote direct synthesis of hydrogen peroxide from H 2 and O 2 over Pd particles. Here, density functional theory based kinetic modeling, augmented with activity measurements and vibrational spectroscopy are used to provide atomistic understanding of direct H 2 O 2 formation over alkylthiolate(RS) Pd. We find that the RS species are oxidized during reaction conditions yielding RSO 2 as the effective ligand. The RSO 2 ligand shows superior ability for proton transfer to the intermediate surface species OOH, which accelerates the formation of H 2 O 2 . The ligands promote the selectivity also by blocking sites for unselective water formation and by modifying the electronic structure of Pd. The work rationalizes observations of enhanced selectivity of direct H 2 O 2 formation over ligand‐funtionalized Pd nanoparticles and shows that engineering of organic surface modifiers can be used to promote desired hydrogen transfer routes.

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

Copper Complexes with Diazoolefin Ligands and their Photochemical Conversion into Alkenylidene Complexes

Homometallic copper complexes with alkenylidene ligands are discussed as intermediates in catalysis but the isolation of such complexes has remained elusive. Herein, we report the structural characterization of copper complexes with bridging and terminal alkenylidene ligands. The compounds were obtained by irradiation of CuI complexes with N-heterocyclic diazoolefin ligands. Furthermore, the complex with a terminal alkenylidene ligand required isolation in a crystalline matrix, and its structural characterization was enabled by in crystallo photolysis at low temperature.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗