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16,526 items found (0 items not approved), displaying 51 to 60.[First/Prev] 2, 3, 4, 5, 6, 7, 8, 9 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I19-Small Molecule Single Crystal Diffraction	A base-free two-coordinate oxoborane Clement R. P. Millet , Dominic R. Willcox , Gary S. Nichol , Cate S. Anstöter , Michael Ingleson Angewandte Chemie International Edition DOI: 10.1002/anie.202419094 Diamond Proposal Number(s): [35994] Open Access Show Abstract ▼ Abstract: Oxoboranes (R-BO) are transient species that rapidly trimerise to form boroxines. To date, the only method used to stabilise oxoboranes is to add a Lewis base, but this forms a three-coordinate at boron oxoborane that has a different bonding/reactivity profile. Herein we report a base-free, two-coordinate oxoborane that is isolated as a Lewis adduct with AlCl3. This species, MesBO-AlCl3 (Mes = 2,4,6-tBu-C6H2), has a ν11ΒΟ stretching frequency of 1843 cm-1, indicating a strong BO bond. Computational analysis indicates this is due to a highly polarised BO bonding interaction combined with modest BO multiple bond character. While the polarisation of the BO bond on AlCl3 coordination enhances the Lewis acidity at boron it also reduces the basicity at oxygen and the latter is key to accessing a base-free oxoborane. Finally, this oxoborane reacts with PhN3 in a unique way to form an unprecedented boron heterocycle.	Nov 2024
I13-2-Diamond Manchester Imaging	Nanoparticle contrast agents for dark-field X-ray imaging Carlos Navarrete-Leon , Adam Doherty , Margarita Strimaite , Joseph C. Bear , Alessandro Olivo , Marco Endrizzi , P. Stephen Patrick Nano Letters DOI: 10.1021/acs.nanolett.4c04878 Diamond Proposal Number(s): [30748] Open Access Show Abstract ▼ Abstract: The poor soft tissue contrast of X-ray CT necessitates contrast agent use to improve diagnosis across disease applications, yet their poor detection sensitivity requires high injected doses, which restrict use in at-risk populations. Dark-field X-ray imaging is emerging as a more sensitive alternative to traditional attenuation-based imaging, leveraging scattered radiation to produce contrast. Yet aside from large, short-lived microbubbles, the alternate physics of dark-field detection has yet to be exploited for contrast agent development. Here we demonstrate that high-Z nanoparticles can provide a new means to producing dark-field image contrast, promoting scatter via a higher rather than lower electron density compared to microbubbles, increasing detection sensitivity compared to attenuation-based detection of a clinical iodine-based agent at an equivalent X-ray dose. As the use of dark-field X-ray imaging expands into more common clinical usage, this will support the development of a new class of nanoparticulate contrast agents.	Nov 2024
I19-Small Molecule Single Crystal Diffraction	Double-bridging increases the stability of Zinc(II) metal-organic cages Hannah Kurz , Paula C. P. Teeuwen , Tanya K. Ronson , Jack B. Hoffman , Philipp Pracht , David J. Wales , Jonathan R. Nitschke Journal Of The American Chemical Society DOI: 10.1021/jacs.4c09742 Diamond Proposal Number(s): [29890] Open Access Show Abstract ▼ Abstract: A key feature of coordination cages is the dynamic nature of their coordinative bonds, which facilitates the synthesis of complex polyhedral structures and their post-assembly modification. However, this dynamic nature can limit cage stability. Increasing cage robustness is important for real-world use cases. Here we introduce a double-bridging strategy to increase cage stability, where designed pairs of bifunctional subcomponents combine to generate rectangular tetratopic ligands within pseudo-cubic Zn8L6 cages. These cages withstand transmetalation, the addition of competing ligands, and nucleophilic imines, under conditions where their single-bridged congeners decompose. Our approach not only increases the stability and robustness of the cages while maintaining their polyhedral structure, but also enables the incorporation of additional functional units in proximity to the cavity. The double-bridging strategy also facilitates the synthesis of larger cages, which are inaccessible as single-bridged congeners.	Nov 2024
I24-Microfocus Macromolecular Crystallography	The crystal structure of human IgD-Fc reveals unexpected differences with other antibody isotypes Anna M. Davies , Tam T. T. Bui , Raúl Pacheco‐gómez , Susan K. Vester , Andrew J. Beavil , Hannah J. Gould , Brian J. Sutton , James M. Mcdonnell Proteins: Structure, Function, And Bioinformatics 125 DOI: 10.1002/prot.26771 Diamond Proposal Number(s): [25301] Open Access Show Abstract ▼ Abstract: Of the five human antibody isotypes, the function of IgD is the least well-understood, although various studies point to a role for IgD in mucosal immunity. IgD is also the least well structurally characterized isotype. Until recently, when crystal structures were reported for the IgD Fab, the only structural information available was a model for intact IgD based on solution scattering data. We now report the crystal structure of human IgD-Fc solved at 3.0 Å resolution. Although similar in overall architecture to other human isotypes, IgD-Fc displays markedly different orientations of the Cδ3 domains in the Cδ3 domain dimer and the lowest interface area of all the human isotypes. The nature of the residues that form the dimer interface also differs from those conserved in the other isotypes. By contrast, the interface between the Cδ2 and Cδ3 domains in each chain is the largest among the human isotypes. This interface is characterized by two binding pockets, not seen in other isotypes, and points to a potential role for the Cδ2/Cδ3 interface in stabilizing the IgD-Fc homodimer. We investigated the thermal stability of IgD-Fc, alone and in the context of an intact IgD antibody, and found that IgD-Fc unfolds in a single transition. Human IgD-Fc clearly has unique structural features not seen in the other human isotypes, and comparison with other mammalian IgD sequences suggests that these unique features might be widely conserved.	Nov 2024
I02-Macromolecular Crystallography I03-Macromolecular Crystallography I24-Microfocus Macromolecular Crystallography	Design and evaluation of pyridinyl sulfonyl piperazine LpxH Inhibitors with potent antibiotic activity against enterobacterales Amanda F. Ennis , C. Skyler Cochrane , Patrick A. Dome , Pyeonghwa Jeong , Jincheng Yu , Hyejin Lee , Carly S. Williams , Yang Ha , Weitao Yang , Pei Zhou , Jiyong Hong Jacs Au DOI: 10.1021/jacsau.4c00731 Diamond Proposal Number(s): [442] Open Access Show Abstract ▼ Abstract: Enterobacterales, a large order of Gram-negative bacteria, including Escherichia coli and Klebsiella pneumoniae, are major causes of urinary tract and gastrointestinal infections, pneumonia, and other diseases in healthcare settings and communities. ESBL-producing Enterobacterales and carbapenem-resistant Enterobacterales can break down commonly used antibiotics, with some strains being resistant to all available antibiotics. This public health threat necessitates the development of novel antibiotics, ideally targeting new pathways in these bacteria. Gram-negative bacteria possess an outer membrane enriched with lipid A, a saccharolipid that serves as the membrane anchor of lipopolysaccharides and the active component of the bacterial endotoxin, causing septic shock. The biosynthesis of lipid A is crucial for the viability of Gram-negative bacteria, and as an essential enzyme in this process, LpxH has emerged as a promising target for developing novel antibiotics against multidrug-resistant Gram-negative pathogens. Here, we report the development of pyridinyl sulfonyl piperazine LpxH inhibitors. Among them, ortho-substituted pyridinyl compounds significantly boost LpxH inhibition and antibiotic activity over the original phenyl series. Structural and QM/MM analyses reveal that these improved activities are primarily due to the enhanced interaction between F141 of the LpxH insertion lid and the pyridinyl group. Incorporation of the N-methyl-N-phenyl-methanesulfonamide moiety into the pyridinyl sulfonyl piperazine backbone results in JH-LPH-106 and JH-LPH-107, both of which exhibit potent antibiotic activity against wild-type Enterobacterales such as K. pneumoniae and E. coli. JH-LPH-107 exhibits a low rate of spontaneous resistance and a high safety window in vitro, rendering it an excellent lead for further clinical development.	Nov 2024
I05-ARPES	Holstein polarons, rashba-like spin splitting, and ising superconductivity in electron-doped MoSe2 Sung Won Jung , Matthew D. Watson , Saumya Mukherjee , Daniil V. Evtushinsky , Cephise Cacho , Edoardo Martino , Helmuth Berger , Timur K. Kim Acs Nano 3 DOI: 10.1021/acsnano.4c07805 Diamond Proposal Number(s): [26631] Open Access Show Abstract ▼ Abstract: Interaction between electrons and phonons in solids is a key effect defining the physical properties of materials, such as electrical and thermal conductivity. In transition metal dichalcogenides (TMDCs), the electron–phonon coupling results in the formation of polarons, quasiparticles that manifest themselves as discrete features in the electronic spectral function. In this study, we report the formation of polarons at the alkali-dosed MoSe2 surface, where Rashba-like spin splitting of the conduction band states is caused by an inversion-symmetry breaking electric field. In addition, we observed a crossover from phonon-like to plasmon-like polaronic spectral features at the MoSe2 surface with increasing doping. Our findings support the concept of electron–phonon coupling-mediated superconductivity in electron-doped layered TMDC materials, as observed using ionic liquid gating technology. Furthermore, the discovered spin-splitting at the Fermi level could offer crucial experimental validation for theoretical models of Ising-type superconductivity in these materials.	Nov 2024
I22-Small angle scattering & Diffraction	Designing and controlling transient supramolecular gels Dave J. Adams , Emma Bowley , Simona Bianco , Fin Hallam Stewart , Chloe Wallace , Rebecca Ginesi , Alex Loch , Martin Rosenthal , Andrew Smith Chemsystemschem DOI: 10.1002/syst.202400073 Diamond Proposal Number(s): [32866] Open Access Show Abstract ▼ Abstract: Supramolecular systems are often designed such that a steady state exists. However, the ability to design systems with pre-determined changes in state can lead to highly dynamic materials, with evolving supramolecular structures and adaptable material properties. This approach is of great interest from the perspective of designing adaptive systems as well as from a broader systems chemistry perspective. Here, we report how a transient system can be altered to access different mechanical properties and transitions by varying the trigger and temperature. The aging of these systems is also explored, as the networks continually evolve long past the common cut-off point of analysis of one day. We therefore provide new insights into the control of transient gels, as well as an understanding as to the underpinning supramolecular structures and how they evolve with time.	Nov 2024
I04-Macromolecular Crystallography	Toxic behaviour: why do tuberculosis bacteria poison themselves? Diamond Light Source Diamond Proposal Number(s): [24948] Show Abstract ▼ Abstract: Stealthy bacteria slow down their division when they invade the body to avoid drawing the immune system's attention. Mycobacterium tuberculosis, the world's leading bacterial infectious killer, takes a seemingly counterintuitive approach to that end. M. tuberculosis expresses self-toxins that damage its DNA and shut down growth as well as antitoxins to later help recuperate and resume proliferation. By studying these toxin-antitoxin pairs, Durham University microbiologist Professor Tim Blower aims to find ways to mimic the self-toxins with new therapeutics.	Nov 2024
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS	Operando characterization of electrochemistry at the rutile TiO2(110)/0.1 M HCl interface using ambient pressure XPS Jiangdong Yu , Conor Byrne , Jameel Imran , Zoe Henderson , Katherine B. Holt , Alexander I. Large , Georg Held , Alex Walton , Geoff Thornton The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.4c07173 Diamond Proposal Number(s): [26045] Open Access Show Abstract ▼ Abstract: Ambient pressure X-ray photoelectron spectroscopy (AP-XPS) was employed to investigate the effect of applied potential on the interface of TiO2(110) with 0.1 M HCl. The study, which involved operando electrochemical characterization, enabled real-time monitoring and analysis of electrochemical processes. There is a significant influence on the interface composition; in particular, the surface Cl– surface coverage varies with electrochemical potential. Moreover, there appears to be a reaction of evolved Cl with adventitious carbon to form C–Cl and C–Cl2 species.	Nov 2024
I06-Nanoscience (XPEEM)	Engineering exchange bias at the interface of self-polarized ultrathin ferroelectric Ba⁢Ti⁢O3 and ferromagnetic La0.67⁢Sr0.33⁢Mn⁢O3 Tuhin Maity , Manisha Bansal , Nives Strkalj , Kapildeb Dolui , Di Zhang , Zihao He , Guillaume F Nataf , Adam Lovett , Massimo Ghidini , Sarnjeet S. Dhesi , Ping Lu , Haiyan Wang , Weiwei Li , Judith L. Macmanus-Driscoll Physical Review Applied 22 DOI: 10.1103/PhysRevApplied.22.054035 Diamond Proposal Number(s): [22427] Open Access Show Abstract ▼ Abstract: We investigate the emergence and optimization of conventional exchange bias (EB) in ultrathin (<10 nm) ferroelectric (FE) Ba⁢Ti⁢O3 (BTO)/ferromagnetic (FM) La0.67⁢Sr0.33⁢Mn⁢O3 (LSMO) epitaxial bilayers without an antiferromagnetic (AFM) material. The EB originates from the electronic orbital reconstruction at the FE-FM interface due to the ferroelectric polarization. We achieve maximum EB of approximately 42 Oe with single-domain polarization in nine-unit-cell-thick BTO, setting the BTO thickness above the critical threshold for ferroelectricity yet below the thickness of strain relaxation and multidomain breakdown. Furthermore, the LSMO layer needs to be thick enough to sustain both the FM layer and polarization-induced AFM spin configuration at the LSMO/BTO interface, yet as thin as possible to enable the EB loop shift. The temperature, training, field, and thickness dependence of the EB confirm that the LSMO/BTO interface exhibits conventional EB despite its unconventional origin. Using x-ray magnetic circular dichroism, scanning transmission electron microscopy, and density-functional-theory calculations, we confirm that the macroscopic EB effect originates from the interfacial AFM spin configuration in LSMO driven by FE-induced d-orbital modifications in interfacial Mn ions. Thus, we engineer strong interfacial EB coupling in artificial multiferroics without a conventional AFM material by controlling FE polarization, highlighting the potential for advanced spintronic applications.	Nov 2024

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