I03-Macromolecular Crystallography
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Diamond Proposal Number(s):
[38144]
Open Access
Abstract: [FeFe]-hydrogenases are the fastest enzymes for hydrogen evolution, yet their irreversible inhibition by oxygen has thwarted their industrial use. CbA5H is an exception as its inhibition by oxygen is reversible. Protein scaffold rearrangement near the active site, allowing a ligand to coordinate the metal center in addition to the formation of a highly oxidized state of the metal center named Hinact, is the current hypothesis for CbA5H oxygen stability. However, the ligand identity has been disputed and there is no evidence to suggest that protein scaffold rearrangement is the sole reason for oxygen stability. Here, we investigate CbA5H oxygen stability by providing a high-resolution (1.96 Å) X-ray structure that shows that the protective ligand is a conserved cysteine thiol group, which directly coordinates the metal center. The local rearrangement also encompasses structural water molecules and the side chain of E341, associated with proton transfer. In addition, we illustrate that C236 and H245, located close to accessory iron sulfur clusters in the Fd domain, influence oxygen stability. We show that mutating these residues significantly decreases oxygen stability but not the ability to form Hinact. Variant C236A displays a slower inactivation rate, which we suggest is due to tuning the redox properties of one of the accessory iron sulfur clusters. We also show that the soluble ligand-binding β-grasp domain (SLBB) may not be required for oxygen stability by comparing CbA5H to a novel homolog lacking this domain. Collectively, these findings expand our understanding of oxygen stability in [FeFe]-hydrogenases.
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Jul 2026
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I03-Macromolecular Crystallography
I04-Macromolecular Crystallography
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Emily J.
Radley
,
Alessia C.
Andrews
,
Indrek
Kalvet
,
Yunling
Deng
,
Elizabeth L.
Bell
,
Colin W.
Levy
,
Mary
Ortmayer
,
Derren J.
Heyes
,
Clare F.
Megarity
,
Reyes
Núñez-Franco
,
Amy E.
Hutton
,
Yi
Lu
,
David
Baker
,
Anthony P.
Green
Diamond Proposal Number(s):
[38021, 31850]
Abstract: Modern protein design methods based on deep learning allow generation of customized protein scaffolds with diverse geometries and functionalities. Here we capitalize on these recent advances to develop hyper-thermostable de novo CO2 reductases featuring a cobalt porphyrin IX (CoPPIX) cofactor. CoPPIX-containing enzymes were assembled in vivo through media supplementation with cobalt salts and assessed for photocatalytic CO2 reductase activity. We identified two cysteine-ligated designs that exhibit high activity (>1000 turnovers at rates of up to 25 min–1) while suppressing competing hydrogen evolution pathways. A 2.1 Å crystal structure shows close agreement to the design model with the Co–Cys bond programmed as intended. This study showcases the power of computational protein design in developing artificial enzymes to activate challenging molecules such as CO2.
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Jul 2026
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I22-Small angle scattering & Diffraction
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Abstract: The Grotthuss mechanism is a proton conduction mechanism where proton transports through the hydrogen-bonding network of water molecules. This mechanism enables high ionic conductivity, which is well utilized in nature and some proton-active artificial devices. Since this mechanism requires cleavage and reformation of hydrogen-bonding networks, its activation energy (Ea) is generally in the range of 10–15 kJ mol–1. Aiming to create a new mechanism beyond the Grotthuss mechanism, we focused on the surface proton hopping conduction (SPHC) mechanism, where a proton hops between neighboring sulfonate groups via bound water molecules. Generally, the SPHC mechanism requires a large Ea. Our idea is that constructing densely aligned sulfonate groups should lead to small Ea (≤10 kJ mol–1) and high proton transport efficiency. To realize high-density alignment of sulfonate groups with an average distance of ca. 5 Å, we employed the self-assembly of a liquid-crystalline (LC) discotic molecule TPES. TPES self-assembled into a hexagonal columnar LC structure in the presence of an appropriate amount of water. The TPES/H2O mixtures showed a maximum proton conductivity of 3.5 × 10–1 S cm–1 at 30 °C and a small Ea of 6.0 kJ mol–1 when the water content X = 53 wt %. We confirmed that extremely fast proton conduction and a small Ea were achieved through only bound water. The dynamics of this bound water were quantitatively evaluated by QENS measurement. These results led us to conclude that the high proton conductivity in the columnar LC materials is primarily based on an extremely activated SPHC mechanism.
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Jun 2026
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[29890]
Open Access
Abstract: The construction of discrete coordination cages using s-block metal ions is challenging due to the weak and electrostatic nature of their coordination bonds, which can lead to the formation of mixtures of products that include intractable coordination polymers, rather than well-defined structures. The alkali and alkaline earth elements are also weaker templates for imines, as they are more oxophilic than transition metals. Here we describe a strategy to overcome these challenges by employing a chelating tris(pyridyl)aldehyde subcomponent to define the vertices of magnesium-templated cages. This subcomponent constrains the flexible coordination sphere of magnesium, enabling the assembly of three distinct coordination cage structure types: edge-bridged and face-capped tetrahedra, and a heteroleptic trigonal prism. These hosts displayed diverse binding properties for a range of guests. The two magnesium-based tetrahedral cages also luminesce upon illumination, a feature absent in their transition-metal counterparts. Our work thus provides a general strategy for accessing discrete s-block coordination cages and introduces magnesium coordination cages as a new class of luminescent supramolecular materials.
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May 2026
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
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Jad
Jaafar
,
Ye
Fan
,
Maryam
Kazemzadeh-Atoufi
,
Ryo
Mizuta
,
Jinfeng
Yang
,
Jack E. N.
Swallow
,
Elizabeth
Jones
,
Matthijs A.
Van Spronsen
,
Georg
Held
,
Robert S
Weatherup
,
Peter
Voorhees
,
David J.
Wales
,
Gabor
Csanyi
,
Stephan
Hofmann
Diamond Proposal Number(s):
[25633]
Open Access
Abstract: The commercialization of emerging materials is hindered by the empirical nature of process development, with the underpinning solid-state reaction kinetics remaining elusive due to their inherent multistep and multiscale character and the vast configurational and parameter space. We combine high-throughput operando scanning electron microscopy (OSEM) with extended classical continuum and phase-field simulations and atomistic machine-learned interatomic potential (MLIP) surrogate models to demonstrate effective foundational reaction exploration, using thermal oxidation of chemical-vapor-deposited monolayer WS2 across a temperature range of 450–680 °C as our benchmark reaction. OSEM provides statistically relevant reaction data sets of spatiotemporal basal plane nucleation kinetics and propagation of tens of thousands of individual 1D reaction facets, revealing time-dependent rates. By extending Avrami theory and employing a calibrated phase-field model, we extract an apparent nucleation barrier of 1.1 eV and show that the complex rate behavior arises from mixed reaction–diffusion control. Atomistic reaction exploration via MLIPs guided by these experimental data reveals that oxidative reaction chains leading to W volatilization and etch pit formation are driven not by the most common sulfur or substitutional oxygen point defects but by more complex defects such as W vacancies. MLIP diffusion barrier screening identifies the role of chemisorbed hydroxyl species for this reaction scenario, while systematic screening of 1D edge configurations and their terminations uncovers the structural origins of the pronounced in-plane reaction anisotropies. We discuss the potential of our synergistic approach to effectively bring experimental and computational approaches closer together and accelerate critically required process discovery for advanced materials.
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May 2026
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B18-Core EXAFS
I11-High Resolution Powder Diffraction
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James M. A.
Steele
,
Joshua D.
Bocarsly
,
Liam A. V.
Nagle-Cocco
,
George S.
Phillips
,
Farheen N.
Sayed
,
Giulio I.
Lampronti
,
Fabio
Orlandi
,
Pascal
Manuel
,
Iuliia
Mikulska
,
Clare P.
Grey
,
Sian E.
Dutton
Diamond Proposal Number(s):
[34243, 32018]
Open Access
Abstract: NaNiO2 is a promising cathode material for sodium-ion batteries due to its high theoretical capacity of 235.8 mAh.g–1. However, as with many Na-ion cathode materials, a series of poorly understood phase transitions occur on electrochemical cycling, inducing volume mismatch-based stress/strain, resulting in particle cracking, electrochemically disconnected particles and, therefore, irreversible capacity loss. This behavior is one key obstacle to developing long-lasting, high-performance Na-ion batteries. Although the series of phases that form as NaxNiO2 is electrochemically cycled have been previously identified, their structures remained unsolved, limiting our ability to understand and control the phase transition behavior. Here, we report structural solutions based on Rietveld refinement against high-resolution synchrotron x-ray diffraction (SXRD) and neutron powder diffraction (NPD) for the phases obtained on desodiation: P″3-Na1/2NiO2, O″3-Na2/5NiO2, and O‴3-Na1/3NiO2. Each phase contains a unique Na+/vacancy ordering, minimizing intralayer electrostatic repulsions between Na+ ions, and Nix+-charge ordering decreasing interlayer repulsions through the location of lower valence Nix+ nearer to vacancies. Using these structures, we conduct sequential Rietveld refinement against operando SXRD data, which supports prior identification of a transient P‴3-Na1/2<x<2/3NiO2 phase, not isolable ex situ. Operando data also identify the presence of a solid-solution phase O″3δ-Na1/3<x<2/5NiO2 and second-order behavior of the O″3-Na2/5NiO2 → O‴3-Na1/3NiO2 phase transition at the top of charge. This work provides unprecedented insight into structural evolution during electrochemical cycling in Ni-rich Na cathodes (and likely Li analogues), paving the way toward rational doping regimes designed to disrupt degradation-inducing phase transitions, increasing capacity and cycle lifetime, thus improving the performance of Co-free Na and Li cathodes.
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May 2026
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B18-Core EXAFS
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Youli
Yu
,
Yifeng
Wang
,
Hanzhi
Ye
,
Sid
Halder
,
Guangmeimei
Yang
,
Boxi
Ye
,
Santosh
Kumar
,
Georg
Held
,
James R.
Durrant
,
Maria-Magdalena
Titirici
,
Reshma R.
Rao
Diamond Proposal Number(s):
[37550, 39622]
Open Access
Abstract: Glycerol oxidation reaction (GOR) is a promising valorization route to upgrade the biodiesel by-product while coproducing green hydrogen at the cathode in electrolyzers. However, the working mechanism of transition-metal-based catalysts such as Ni(OH)2 remains poorly understood. Here, we employed a multioperando spectroelectrochemical approach combining UV–vis optical spectroscopy, X-ray absorption spectroscopy, and time-resolved stepped-potential spectroscopy to investigate the active oxidizing species and charge-transfer dynamics under OER and GOR conditions. We identified NiOOH (Ni3+) as the active species for GOR, whereas the formation of higher-valent NiOO (Ni4+) species is completely suppressed in the presence of glycerol. The accumulation of surface-adsorbed glycerol molecules is the rate-determining step (τ ∼ 27.9 s at 1.47 VRHE), occurring slower than the intrinsic catalytic step of glycerol reaction (τ ∼ 3.2 s at 1.47 VRHE), which involves oxidation and bond cleavage. In contrast, the kinetics of the OER are significantly slower (τ ∼ 167 s at 1.47 VRHE), resulting in the dominance of GOR and suppression of oxygen evolution in the presence of glycerol. The potential-independent production of formic acid during GOR follows an apparent first-order dependence on NiOOH concentration, suggesting continuous C–C bond cleavage activated by reactive *O species. These findings link oxidizing species with charge-transfer dynamics, providing insight for the rational design of Ni-based catalysts for glycerol and other biomass-derived molecule oxidations.
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Apr 2026
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B18-Core EXAFS
I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[34409, 37864, 35948]
Open Access
Abstract: The persistent contamination of water sources by perfluorooctanoic acid (PFOA) poses a major environmental and public health challenge. PFOA is a representative member of per- and polyfluoroalkyl substances (PFAS), a class of compounds characterized by high chemical stability, bioaccumulation potential, and toxicity. Conventional water treatment processes are not fully effective in removing PFOA, underscoring the urgent need for advanced remediation strategies. Here, we report the development of Fe-MOF-808, a novel porous material obtained by incorporating binuclear iron species into the Zr6O8 nodes of the MOF-808 framework. Comprehensive structural characterization was performed, including ex/in situ synchrotron-based techniques combined with computational modeling. The results confirm successful iron integration without compromising the structural integrity and accessibility of the porous network. Moreover, the presence of multiple, spatially accessible binding sites enables Fe-MOF-808 to capture PFAS through a combination of electrostatic, hydrophobic and coordinative interactions. This resulted in high removal efficiencies across various water matrices and for a wide range of PFAS pollutants and concentrations. Fe-MOF-808 notably achieves complete PFOA removal within minutes and demonstrates excellent recyclability over multiple adsorption cycles. The material also reaches experimental uptake and a maximum Langmuir adsorption capacity of 2081 and 3120 mg PFOA g–1, respectively, vastly outperforming the pristine MOF-808 and other state-of-the-art MOF materials. Overall, mechanistic insights gained from this study highlight the critical role of designing specific chemical environments within MOFs to maximize pollutant-sorbent interactions.
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Apr 2026
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B22-Multimode InfraRed imaging And Microspectroscopy
I11-High Resolution Powder Diffraction
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Shan
Dai
,
Longzhang
Dong
,
Yinlin
Chen
,
Jiangnan
Li
,
Justyna
Rogacka
,
Yuhang
Yang
,
Zi
Wang
,
Benjamin J.
Moore
,
Daniel
Lee
,
Yongqiang
Cheng
,
Svemir
Rudic
,
Bogdan
Kuchta
,
Mark D.
Frogley
,
Lucy
Saunders
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[39702, 41731]
Abstract: The desulfurization of flue gas requires sorbents capable of selective and reversible SO2 capture. However, top-performing materials operate through either strong binding sites or the use of narrow pores, leading to difficulties in desorption and materials regeneration. Here, we report the efficient capture of trace SO2 using a robust and scalable aluminum-based metal–organic framework, MIL-120, which shows an exceptional SO2 uptake of 2.1 mmol g–1 at 2500 ppm and 298 K, coupled with optimal heats of adsorption (19–42 kJ mol–1) and fully reversible desorption at room temperature. Direct visualization of adsorbed SO2 molecules reveals host–guest and guest–guest interactions, collectively affording an SO2 packing density of 1.92 g cm–3, formally surpassing that of solid SO2 (1.62 g cm–3). Breakthrough experiments demonstrate that MIL-120 exhibits remarkable trace SO2 capture in the presence of dry or wet NO2 (another corrosive gas present in flue gas) with a record dynamic selectivity of 124, confirming the potential for MIL-120 to separate SO2/NO2 mixtures. This work sets a new benchmark for sorbent materials for reversible trace SO2 capture and separation.
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Apr 2026
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[34842]
Abstract: The development of high-performance infrared (IR) nonlinear optical (NLO) crystals is fundamentally challenged by the conflicting requirements for a large NLO coefficient, a high laser damage threshold (LDT), and a broad IR transparency range. We establish a structure–property relationship governing nonlinear optical response in diamond-like compounds, namely, a sixth-power scaling relation between the NLO coefficient dijk and average flexibility index F, i.e., dijk ∝ F6. Based on this relation, a multiple flexible-group synergistic polarization strategy is proposed, which successfully guided the discovery of an exceptional IR NLO crystal, Cd2In3Si2P7 (CISP). CISP exhibits the largest recorded SHG effect (8.8 × AgGaS2 (AGS) and 2.5 × ZnGeP2 (ZGP) @ 2050 nm) among reported pnictide NLO crystals, high NLO coefficients (d22 and d23 = 137.6 and 89.3 pm/V @ 1500 nm, respectively), a high LDT (10.3 × AGS), a moderate birefringence (0.098 @ 2050 nm), and a broad IR transmission range (0.62–18.0 μm). The outstanding comprehensive performances underscore its significant potential as a promising IR NLO material. This work not only provides a strategy for the design of IR NLO crystals but also introduces a straightforward yet powerful descriptor for understanding the structure–property correlation in polarizable functional materials.
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Apr 2026
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