I19-Small Molecule Single Crystal Diffraction
|
Diamond Proposal Number(s):
[21755, 28766]
Open Access
Abstract: Previously inaccessible large S8-corona[n]arene macrocycles (n = 8-12) with alternating aryl and 1,4-C6F4 subunits are easily prepared on up to gram scales, without the need for chromatography (up to 45% yield, 10 different examples) through new high acceleration SNAr subsitution protocols (catalytic NR4F in pyridine, R = H, Me, Bu). Macrocycle size and functionality are tunable by precursor and catalyst selection. Equivalent simple NR4F catalysis allows facile late-stage SNAr difunctionalisation of the ring C6F4 units with thiols (8 derivatives, typically 95+% yields) providing two-step access to highly functionalised fluoromacrocycle libraries. Macrocycle host binding supports fluoroaryl catalytic activation through contact ion pair binding of NR4F and solvent inclusion. In the solid-state, solvent inclusion also intimately controls macrocycle conformation and fluorine-fluorine interactions leading to spontaneous self-assembly into infinite columns with honeycomb-like lattices.
|
Nov 2022
|
|
I14-Hard X-ray Nanoprobe
|
Mandar
Bandekar
,
Fazel
Abdolahpur Monikh
,
Jukka
Kekäläinen
,
Teemu
Tahvanainen
,
Raine
Kortet
,
Peng
Zhang
,
Zhiling
Guo
,
Jarkko
Akkanen
,
Jari T. T.
Leskinen
,
Miguel A.
Gomez-Gonzalez
,
Gopala
Krishna Darbha
,
Hans-Peter
Grossart
,
Eugenia
Valsami-Jones
,
Jussi V. K.
Kukkonen
Diamond Proposal Number(s):
[30433]
Open Access
Abstract: The smallest fraction of plastic pollution, submicron plastics (SMPs <1 μm) are expected to be ubiquitous in the environment. No information is available about SMPs in peatlands, which have a key role in sequestering carbon in terrestrial ecosystems. It is unknown how these plastic particles might behave and interact with (micro)organisms in these ecosystems. Here, we show that the chemical composition of polystyrene (PS) and poly(vinyl chloride) (PVC)-SMPs influenced their adsorption to peat. Consequently, this influenced the accumualtion of SMPs by Sphagnum moss and the composition and diversity of the microbial communities in peatland. Natural organic matter (NOM), which adsorbs from the surrounding water to the surface of SMPs, decreased the adsorption of the particles to peat and their accumulation by Sphagnum moss. However, the presence of NOM on SMPs significantly altered the bacterial community structure compared to SMPs without NOM. Our findings show that peatland ecosystems can potentially adsorb plastic particles. This can not only impact mosses themselves but also change the local microbial communities.
|
Nov 2022
|
|
I19-Small Molecule Single Crystal Diffraction
|
Diamond Proposal Number(s):
[23480]
Open Access
Abstract: Ethylene-bridged oligoureas are dynamic foldamers in which the polarity of a coherent chain of intramolecular hydrogen bonds may be controlled by intra- or intermolecular interactions with hydrogen-bond donors or acceptors. In this paper, we describe the way that supramolecular interactions between ethylene-bridged oligoureas bearing a 3,5-bis(trifluoromethyl)phenylurea (BTMP) terminus leads to higher-order structures both in the crystalline state and in solution. The oligoureas self-assemble by head-to-tail hydrogen bonding interactions to form either supramolecular ‘nanorings’ with cyclic hydrogen bond chain directionality, or supramolecular helical chains of hydrogen bonds. The self-assembly process features a cascade of cooperative positive allostery, in which each intermolecular hydrogen bond formation at the BTMP terminus switches the native hydrogen bond chain directionality of monomers, favouring further assembly. Monomers with a benzyl urea terminus self-assemble into nanorings, whereas monomers with a N-ethyl urea terminus form helical chains. In the crystal state, parallel helices have identical handedness and polarity, whereas antiparallel helices have opposite handedness. The overall dipole moment of crystals is zero due to the antiparallel arrangements of local dipoles in the crystal packing. Supramolecular interactions in solution were also examined by VT and DOSY NMR spectroscopy, up to the point of crystal formation. The size of higher aggregates in dichloromethane was estimated by their hydrodynamic radius. The relative orientation of the monomers within the aggregates, determined by 2D ROESY NMR, was the same as in the crystals, where syn-orientations lead to the formation of rings and anti-orientations result in chains. Overall, the switch of hydrogen bond polarity propagates intermolecularly in crystal and solution states, constituting an example of intermolecular communication within supramolecular polymers.
|
Nov 2022
|
|
B18-Core EXAFS
I20-Scanning-X-ray spectroscopy (XAS/XES)
|
Diamond Proposal Number(s):
[21441, 24074]
Open Access
Abstract: Over 60 years of nuclear activity have resulted in a global legacy of contaminated land and radioactive waste. Uranium (U) is a significant component of this legacy and is present in radioactive wastes and at many contaminated sites. U-incorporated iron (oxyhydr)oxides may provide a long-term barrier to U migration in the environment. However, reductive dissolution of iron (oxyhydr)oxides can occur on reaction with aqueous sulfide (sulfidation), a common environmental species, due to the microbial reduction of sulfate. In this work, U(VI)–goethite was initially reacted with aqueous sulfide, followed by a reoxidation reaction, to further understand the long-term fate of U species under fluctuating environmental conditions. Over the first day of sulfidation, a transient release of aqueous U was observed, likely due to intermediate uranyl(VI)–persulfide species. Despite this, overall U was retained in the solid phase, with the formation of nanocrystalline U(IV)O2 in the sulfidized system along with a persistent U(V) component. On reoxidation, U was associated with an iron (oxyhydr)oxide phase either as an adsorbed uranyl (approximately 65%) or an incorporated U (35%) species. These findings support the overarching concept of iron (oxyhydr)oxides acting as a barrier to U migration in the environment, even under fluctuating redox conditions.
|
Nov 2022
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
Diamond Proposal Number(s):
[16214]
Open Access
Abstract: Laser powder bed fusion (LPBF) can produce high-value metallic components for many industries; however, its adoption for safety-critical applications is hampered by the presence of imperfections. The interdependency between imperfections and processing parameters remains unclear. Here, the evolution of porosity and humps during LPBF using X-ray and electron imaging, and a high-fidelity multiphase process simulation, is quantified. The pore and keyhole formation mechanisms are driven by the mixing of high temperatures and high metal vapor concentrations in the keyhole is revealed. The irregular pores are formed via keyhole collapse, pore coalescence, and then pore entrapment by the solidification front. The mixing of the fast-moving vapor plume and molten pool induces a Kelvin–Helmholtz instability at the melt track surface, forming humps. X-ray imaging and a high-fidelity model are used to quantify the pore evolution kinetics, pore size distribution, waviness, surface roughness, and melt volume under single layer conditions. This work provides insights on key criteria that govern the formation of imperfections in LPBF and suggest ways to improve process reliability.
|
Oct 2022
|
|
I04-1-Macromolecular Crystallography (fixed wavelength)
|
Open Access
Abstract: Bacteroides fragilis is an abundant commensal component of the healthy human colon. However, under dysbiotic conditions, enterotoxigenic B. fragilis (ETBF) may arise and elicit diarrhea, anaerobic bacteremia, inflammatory bowel disease, and colorectal cancer. Most worrisome, ETBF is resistant to many disparate antibiotics. ETBF's only recognized specific virulence factor is a zinc-dependent metallopeptidase (MP) called B. fragilis toxin (BFT) or fragilysin, which damages the intestinal mucosa and triggers disease-related signaling mechanisms. Thus, therapeutic targeting of BFT is expected to limit ETBF pathogenicity and improve the prognosis for patients. We focused on one of the naturally occurring BFT isoforms, BFT-3, and managed to repurpose several approved drugs as BFT-3 inhibitors through a combination of biophysical, biochemical, structural, and cellular techniques. In contrast to canonical MP inhibitors, which target the active site of mature enzymes, these effectors bind to a distal allosteric site in the proBFT-3 zymogen structure, which stabilizes a partially unstructured, zinc-free enzyme conformation by shifting a zinc-dependent disorder-to-order equilibrium. This yields proBTF-3 incompetent for autoactivation, thus ablating hydrolytic activity of the mature toxin. Additionally, a similar destabilizing effect is observed for the activated protease according to biophysical and biochemical data. Our strategy paves a novel way for the development of highly specific inhibitors of ETBF-mediated enteropathogenic conditions.
|
Oct 2022
|
|
B21-High Throughput SAXS
|
Fabian
Heide
,
Scott
Legare
,
Vu
To
,
Monika
Gupta
,
Haben
Gabir
,
Thomas
Imhof
,
Aniel
Moya-Torres
,
Matthew
Mcdougall
,
Markus
Meier
,
Manuel
Koch
,
Jörg
Stetefeld
Diamond Proposal Number(s):
[22113]
Abstract: Extracellular matrix proteins are most often defined by their direct function that involves receptor binding and subsequent downstream signaling. However, these proteins often contain structural binding regions that allow for the proper localization in the extracellular space which guides its correct function in a local and temporal manner. The regions that serve a structural function, although often associated with disease, tend to have a limited understanding. An example of this is the extracellular matrix protein Noggin; as part of the bone morphogenetic protein inhibitor family, Noggin serves a crucial regulatory function in mammalian developmental stages and later periods of life. Noggin's regular function, after its expression and extracellular release, is mediated by its retention in close proximity to the cellular surface by glycosaminoglycans, specifically heparin and heparan sulfate. Using a biophysical hybrid method approach, we present a close examination of the Noggin heparin binding interface, study its dynamic binding behaviors and observe supramolecular Noggin assemblies mediated by heparin ligands. This confirms previously suggested models of non-covalent protein assemblies mediated through glycosaminoglycans that exist in the extracellular matrix. Further, structural analyses through molecular dynamics simulations allowed us to determine contribution energies for each protein residue involved in ligand binding and correlate this to disease associated mutation data. Our combination of various biophysical and computational methods that characterize the heparin binding interface on Noggin and its protein dynamics expands on the functional understanding of Noggin and can readily be applied to other protein systems.
|
Sep 2022
|
|
B18-Core EXAFS
|
Diamond Proposal Number(s):
[18835]
Abstract: Mesoporous AlPO4 materials have attracted much attention in catalysis due to their high thermal and chemical stability. Of particular interest for catalysis is the pure stoichiometry high surface area (> 500 m2/g) mesoporous AlPO4 (mAlPO4) glass prepared via a template-free aqueous sol–gel synthetic route. Toward the application of this material for catalysis, we have developed methods for loading it with nanoparticles (NPs) of catalytic metals—Pd and Rh—and carried out a detailed characterization study of the resulting doped materials by a wide array of analytical methods, including synchrotron X-ray absorption spectroscopy, inelastic neutron scattering and more. The applicability of this material for catalysis, both by itself and as a support for catalytic NPs, was then evaluated. The pure mAlPO4 exhibited excellent acid-catalyzed [3 + 2] cycloaddition of nitriles and sodium azide. mAlPO4 loaded with the Pd NPs catalyzed very efficiently deoxygenation reactions of benzyl alcohols. mAlPO4 loaded with Rh NPs catalyzed with high selectivity, the hydrogenation of phenols and cresols and full conversion the hydrogenation of the industrially very high-volume toluene to methylcyclohexane. The materials-science aspects of these successful catalysts were studied in detail, leading, for instance, to the understanding of the important role of the interfacial Rh/Pd–O-P bonds.
|
Sep 2022
|
|
Detectors
|
David
Omar
,
Giulio
Crevatin
,
Alan
Greer
,
Ian
Horswell
,
Jonathan
Spiers
,
Richard
Plackett
,
Paul
Booker
,
Gale
Lockwood
,
Dan
Beckett
,
Emily
Galvin
,
John
Lipp
,
Michelangelo
Di Palo
,
Mark
Warren
,
Scott
Williams
,
Nicola
Tartoni
Open Access
Abstract: This paper describes the development of the Tristan 10M detector for time resolved synchrotron experiments. Tristan 10M has an unprecedented time resolution (ns time scale) over long duration continuous acquisition (days). The detector is constructed from an array of 160 Timepix3 readout ASIC (about 10 million pixels) flip chip bonded to 10 monolithic silicon sensors which enable it to cover an area large enough to effectively carry out crystallography experiments. The large array of ASICs resulted in a number of severe technical challenges that had to be overcome during the development of the detector. The minimization of the dead area between sensors required the development of a very challenging mechanical and electronic packaging. Such a packaging had to be able to route the large number of data and power lines within the footprint of a sensor, had to effectively sink the heat generated by the ASICs, and had to be able to position the sensors accurately. In addition, the packaging of the detector was designed to be scalable in consideration of possible future larger versions of this detector which added a further challenge. The data driven nature of Timepix3 and the sheer data volume produced by the array of ASICs required us to devise a dedicated hardware, firmware, and software data acquisition architecture. This architecture proved very effective during the commissioning of Tristan10M when time resolved crystallography experiments were carried out.
|
Sep 2022
|
|
I18-Microfocus Spectroscopy
|
Diamond Proposal Number(s):
[31047, 26697]
Open Access
Abstract: Semiconductors in their optical-fiber forms are desirable. Single-crystal organometallic halide perovskites have attractive optoelectronic properties and therefore are suitable fiber-optic platforms. However, single-crystal organometallic perovskite optical fibers have not been reported before due to the challenge of one-directional single-crystal growth in solution. Here, we report a solution-processed approach to continuously grow single-crystal organometallic perovskite optical fibers with controllable diameters and lengths. For single-crystal MAPbBr3 (MA = CH3NH3+) perovskite optical fiber made using our method, it demonstrates low transmission losses (<0.7 dB/cm), mechanical flexibilities (a bending radius down to 3.5 mm), and mechanical deformation–tunable photoluminescence in organometallic perovskites. Moreover, the light confinement provided by our organometallic perovskite optical fibers leads to three-photon absorption (3PA), in contrast with 2PA in bulk single crystals under the same experimental conditions. The single-crystal organometallic perovskite optical fibers have the potential in future optoelectronic applications.
|
Sep 2022
|
|
