I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[35994]
Abstract: Gold catalysis provides access to a remarkable array of complex carbon scaffolds, but the use of silver salts to activate gold(I) chloride precatalysts can be problematic due to Ag(I) light sensitivity, hygroscopicity, redox activity, and interference with the desired catalysis. Although H-bond donors are a promising alternative to silver salts, they still suffer from much lower activity and narrower applicability, as Au–Cl cleavage remains rate limiting. To address these limitations, we have rationally designed a self-activating phosphine Au(I) chloride complex that incorporates a supramolecular chloride receptor in the form of an anthracene bisurea quintuple H-bond donor. In the absence of any additive, this complex promotes multiple intra- and intermolecular reactions, with a catalytic activity rivalling traditional inorganic chloride scavengers. Mechanistic studies for the model reaction show that the exceptional chloride binding ability of the anthracene bisurea unlocks access to a zwitterionic catalyst resting state where the Au─Cl bond has been cleaved, thus significantly reducing barriers for catalysis. The principles uncovered in this work show how supramolecular anion recognition moieties impact catalyst speciation and enhance performance, enabling for the first time H-bond donors to compete with inorganic chloride scavengers in terms of activity and generality.
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Jan 2026
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I15-1-X-ray Pair Distribution Function (XPDF)
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Jamie L.
Cleron
,
Chih-Yi
Chen
,
Feng
Pan
,
Santanu
Saha
,
Frederick P.
Marlton
,
Robert M.
Stolz
,
Jiayi
Li
,
Jennifer A.
Dionne
,
Fang
Liu
,
Marina R.
Filip
,
Hemamala I.
Karunadasa
Diamond Proposal Number(s):
[40486]
Open Access
Abstract: Self-assembly affords simpler synthetic routes to heterostructures compared with manual layer-by-layer stacking, yet controlling interlayer twist angles in a bulk solid remains an outstanding challenge. We report two new single-crystal heterostructures: (Sn2Cl2)(CYS)2SnCl4 (CYS = +NH3(CH2)2S–; Sn_CYS) and (Sn2Cl2)(SeCYS)2SnCl4 (SeCYS = +NH3(CH2)2Se–; Sn_SeCYS) synthesized in solution, with alternating perovskite and intergrowth layers. Notably, compared to the recently reported lead analog, (Pb2Cl2)(CYS)2PbCl4 (Pb_CYS), the tin heterostructures feature a twist between the perovskite and intergrowth layers. We trace this twist to local distortions at the Sn centers, which change the interfacial lattice-matching requirements compared to those of the Pb analog. Electronic band structure calculations show that the striking differences in the relative energies of perovskite- and intergrowth-derived bands in Sn_CYS and Pb_CYS arise from structural and not compositional differences. The structural anisotropy of Sn_CYS is also reflected in a large in-plane photoluminescence linear anisotropy ratio. Interfacial strain further affords differential incorporation of Pb into the perovskite and intergrowth layers of the Sn heterostructures, resulting in redshifted optical absorption onsets. Thus, we posit that local structural distortions may be exploited to manipulate the twist angle and interfacial strain in bulk heterostructures, providing a new handle for tuning the band alignments of bulk quantum-well electronic structures.
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Dec 2025
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B18-Core EXAFS
E01-JEM ARM 200CF
I09-Surface and Interface Structural Analysis
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Thomas J.
Liddy
,
Benjamin J.
Young
,
Emerson C.
Kohlrausch
,
Andreas
Weilhard
,
Gazi N.
Aliev
,
Yifan
Chen
,
Manfred E.
Schuster
,
Mohsen
Danaie
,
Luke L.
Keenan
,
Donato
Decarolis
,
Diego
Gianolio
,
Siqi
Wang
,
Mingming
Zhu
,
Graham J.
Hutchings
,
David M.
Grant
,
Wolfgang
Theis
,
Tien-Lin
Lee
,
David A.
Duncan
,
Alberto
Roldan
,
Andrei N.
Khlobystov
,
Jesum
Alves Fernandes
Diamond Proposal Number(s):
[38764]
Open Access
Abstract: Ammonia is an attractive hydrogen carrier, yet its practical use is limited by the need for efficient catalytic decomposition. We demonstrate that in-situ N-doping of Ru nanoparticles and graphitized carbon nanofiber supports during reaction produces a sharp increase in hydrogen production during the first 40 h, followed by stable activity. Spectroscopic and microscopic analyses, together with density functional theory simulations, reveal that Ru nitridation is rapid and support-independent, resulting in a mechanistic shift from the traditional Langmuir–Hinshelwood to a Mars–van Krevelen pathway, further confirmed by isotopic labelling experiments. In contrast, the progressive nitridation of the carbon support, observed via X-ray photoelectron spectroscopy, modulates the electronic environment of Ru and functions as a dynamic nitrogen reservoir that enables reversible N atoms exchange with the Ru particles, facilitating N desorption from the Ru surface and thereby governing the catalytic activity enhancement. These new findings provide new mechanistic insight into ammonia decomposition and establish progressive nitrogen doping of carbon supports as a strategy for designing efficient metal-based catalysts for hydrogen production.
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Dec 2025
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I22-Small angle scattering & Diffraction
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Open Access
Abstract: A liquid crystal (LC) polymethylsiloxane (PMS) with rod-like aromatic side-groups attached via an alkylene spacer and bearing three n-dodecyl end-tails is found to form an unusual cubic structure. In a normal LC double gyroid (DG), the two chiral subspaces, one each side of the G-surface, are occupied by one network each. Here each such network is split into two aromatic strands that wind around the central polysiloxane bundle, forming a double helix, resulting in a four-network gyroid (4NG). While in previous normal LC DGs the network twist was assumed to follow that of the subspace, in 4NG the twist sense of the double-helix is opposite to that of the subspace., i.e., while a right-handed subspace twists by +70.5° between junctions, the double-helix “supertwists” by −109.5°, and the opposite is true for the left-handed subspace. Detailed analysis by X-ray diffraction, DSC, and depolarized fluorescence (DF) shows a gradual but significant reversible change in the degree of mixing between the aromatic side groups and the polysiloxane backbones at 120 °C–130 °C in 4NG. Also, a significant increase in the system mobility starts only at ∼40 °C above the melting point, indicating persistence of local double-helical segments even in the melt.
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Dec 2025
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[14657]
Open Access
Abstract: Learning to control reaction kinetics is essential for translating any chemical technology into real-world application. Based on time-resolved in situ powder X-ray diffraction data, we demonstrate the opportunity to tune mechanochemical reaction rates through the pre-activation of the starting reagents. For three model co-crystal systems, the pre-activation of the most stable reagent yields up to a ca 10-fold increase in the reaction rate, whilst negligible kinetic enhancement is seen when the less stable reagent is pre-activated. Moreover, we demonstrate how the polymorphic outcome of mechano-co-crystallization is also sensitive to pre-activation of the starting material. Our results suggest that reproducibility of mechanochemical processes requires detailed understanding over the origin and history of reagent powders, whilst providing a new conceptual framework to design and control mechanochemical reactions.
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Nov 2025
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I04-1-Macromolecular Crystallography (fixed wavelength)
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Serena G.
Piticchio
,
Miriam
Martinez-Cartro
,
Salvatore
Scaffidi
,
Sergio
Rodríguez-Arévalo
,
Andrea
Bagán
,
Ainoa
Sánchez-Arfelis
,
Sarah
Picaud
,
Tobias
Krojer
,
Panagis
Filippakopoulos
,
Carmen
Escolano
,
Xavier
Barril
,
Frank
Von Delft
Diamond Proposal Number(s):
[19301]
Open Access
Abstract: The hydrophobic effect is a central force in molecular recognition, typically attributed to the ordering of water molecules around apolar groups. Hydrophobic interaction sites on proteins are therefore readily predicted based on surface polarity. Yet, in the bromodomain-containing protein 4 (BRD4), a well-known hydrophobic hot spot is paradoxically lined by a network of water molecules. Here we combine binding assays, structural data, molecular dynamics, and free-energy calculations to resolve this apparent contradiction. We show that the water network functions as a hydrophobic recognition motif that cannot accommodate polar groups without disruption. Instead, as the protein pre-organizes the water network, apolar groups can bind with minimal entropic cost. In turn, they reinforce the surrounding hydrogen-bond network, limiting the mobility of the entire protein–water assembly. With this perspective, we identify water networks potentially functioning as hydrophobic motifs in other pharmacological targets, revealing a general but overlooked recognition element with broad implications in drug discovery and protein design.
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Nov 2025
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B18-Core EXAFS
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Qingqing
Mei
,
Wenyuan
Huang
,
Longfei
Lin
,
Xue
Han
,
Shaojun
Xu
,
Bing
An
,
Svemir
Rudic
,
Rongsheng
Cai
,
Sarah J.
Haigh
,
Buxing
Han
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[36450]
Open Access
Abstract: The synthesis of organic amines via reductive amination of biomass-derived carbonyl compounds is an important target for sustainable chemical industries. The control of selectivity for the formation of primary amines versus secondary amines is challenging, and high temperature and pressures using H2 are required to generate the desired selectivity. Herein, we report the highly selective reductive amination of a broad range of aldehydes and ketones by NH3 and H2 over Rh/MFM-300(Cr) to form primary amines with a selectivity of up to 99% under ambient conditions. Inelastic neutron scattering reveals that the Rh species not only promote the hydrogenation process, but also catalyzes the ammonolysis of the Schiff base intermediate, facilitating the selective synthesis of primary amines. This protocol achieves selective reductive amination at 25 °C and 1 atm, providing an energy-efficient route to a broad spectrum of amines.
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Nov 2025
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B23-Circular Dichroism
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Mateusz
Pawlak
,
Julia
Abramowicz
,
Nadesh
Fiuza Maneiro
,
Gail A.
Vinnacombe-Willson
,
Sunghwan
Jo
,
Elie
Benchimol
,
Piotr
Roszkowski
,
Zitao
Chen
,
Da
Wang
,
Guido H.
Clever
,
Luis M.
Liz-Marzán
,
Agustín
Mihi
,
Lakshminarayana
Polavarapu
,
Wiktor
Lewandowski
Diamond Proposal Number(s):
[34852, 38639]
Open Access
Abstract: Perovskite nanocrystals (PNCs) exhibiting circularly polarized luminescence (CPL) represent a promising class of materials for display and light communication technologies, owing to their emission covering the entire visible range with near-unity photoluminescence efficiency. However, these materials suffer from low selectivity in the handedness of the emitted light, with most studies focusing on green emission. We address these issues by exploiting and broadening the scope of interactions between achiral PNCs and chiral organic templates. For this purpose, we select three types of PNCs with red, green, and blue emissions and introduce them into a chiral liquid-crystalline matrix in the form of composite thin films. Electron microscopy confirmed the assembly of PNCs within nanoscale gaps formed by supramolecular, liquid crystalline structures. The obtained composites displayed a CPL dissymmetry factor glum up to ≈ 0.24. The highly dissymmetric CPL properties were found to result from an interplay between two effects: chiral assembly of PNCs within a chiral environment (intrinsic) and the selective filtering by the chiral matrix. This system enables control over the dominant factors by adjusting the CPL spectral region and type of particle assembly, providing thin film materials with highly dissymmetric and spectrally tunable CPL responses.
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Nov 2025
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[35981]
Open Access
Abstract: The mechanism of nanoparticle formation during reverse sequence polymerization-induced self-assembly (PISA) is studied by small-angle X-ray scattering (SAXS). More specifically, N,N′-dimethylacrylamide (DMAC) monomer is added to a trithiocarbonate-capped poly(ɛ-caprolactone) (PCL) precursor and initially polymerized in the bulk at 80 °C via reversible addition-fragmentation chain transfer (RAFT) polymerization. SAXS indicates the unexpected formation of molten PCL droplets dispersed within DMAC monomer. After 5 min (14% DMAC conversion) at 80 °C, the reaction mixture is diluted with water, and the aqueous milieu is analyzed using a flow cell. A transient lamellar phase is formed immediately after water addition that subsequently transforms into nascent spherical nanoparticles. During the remaining DMAC polymerization, the overall nanoparticle diameter remains essentially constant with a concomitant reduction in the PCL core radius and the aggregation number. This suggests that individual PCL-PDMAC chains are in equilibrium with the nanoparticles. SAXS analysis indicates that the amorphous PCL cores have a mean diameter of 8.8 nm at 80 °C: X-ray diffraction (XRD) studies confirm that such nanoscale confinement prevents their crystallization on cooling to 20 °C. Finally, this formulation can be combined with crystallization-driven self-assembly (CDSA): UV-initiated DMAC polymerization at 15 °C produces rod-like PCL-PDMAC nanoparticles with semicrystalline PCL cores.
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Nov 2025
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[36397]
Abstract: Despite remaining enigmatic, strong hydrogen bonding provides an advanced design handle for tailoring the properties of functional materials. Here, 3R–(H/D)RhO2 delafossites (prepared by ion exchange of Na+ from NaRhO2) contain H/D in linear coordination with O, linking RhIIIO2 layers. Bragg and real-space X-ray and neutron scattering analysis, vibrational and solid-state NMR spectroscopy, and density functional theory (DFT)–based electronic structure calculations have been employed to understand the nature of the hydrogen bonding. Despite short distances between H/D and the two O to which they are bonded, a clear double-minimum corresponding to a shorter and longer (H/D)–O distance is established. The triangular lattices formed by H/D appear to display ice-like disorder, corroborated by low-temperature heat capacity measurements.
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Nov 2025
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