E01-JEM ARM 200CF
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Hui
Luo
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Nikolaos
Papaioannou
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Enrico
Salvadori
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Maxie
Roessler
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Gereon
Ploenes
,
Ernst R. H.
Van Eck
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Liviu
Tanase
,
Jingyu
Feng
,
Yiwei
Sun
,
Yan
Yang
,
Mohsen
Danaie
,
Ana
Jorge Sobrido
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Andrei
Sapelkin
,
James
Durrant
,
Stoichko D.
Dimitrov
,
Maria-magdalena
Titirici
Diamond Proposal Number(s):
[17587]
Abstract: As a new class of sustainable carbon material, the term “carbon dots” represents an “umbrella term” as there are many types of materials included. We employ a broad range of techniques to develop understanding on hydrothermally synthesized carbon dots and show how fine tuning the structural features using simple reduction/oxidation reactions can drastically affect their excited state properties. Structural and spectroscopic studies found that photoluminescence originates from direct excitation of localized fluorophores involving oxygen functional groups, while the excitation at graphene‐like features leads to ultrafast phonon‐assisted relaxation and largely quenches the fluorescent quantum yields. This is arguably the first to identify the dynamics of photoluminescence including Stokes’ shift formation, allowing us to fully resolve the relaxation pathways in these carbon dots. The comprehensive investigation sheds light on how understanding the excited state relaxation processes in different carbon structure is crucial for tuning the optical properties for any potential commercial applications.
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Aug 2019
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[20638]
Abstract: We report the precise postsynthetic control of the composition of β‐Fe1+xSe by electrochemistry with simultaneous tracking of the associated structural changes via in‐situ synchrotron X‐ray diffraction. We access the full phase width of 0.01 < x < 0.04 and identify the superconducting state below 8 K, which in contrast to earlier reports is independent of the composition. However, in a second set of in‐situ X‐ray diffraction experiments, we demonstrate that β‐Fe1+xSe forms a new phase in the presence of oxygen above a 100 °C which has the same anti‐PbO type structure but is not superconducting down to 1.8 K. The latter process can be reversed electrochemically to reinstate the superconducting state. These observations exploit the exquisite control afforded by electrochemistry in contrast with classical approaches of chemical synthesis.
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Aug 2019
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Paul
Bamborough
,
Chun-wa
Chung
,
Emmanuel H.
Demont
,
Angela M.
Bridges
,
Peter D.
Craggs
,
David P.
Dixon
,
Peter
Francis
,
Rebecca C.
Furze
,
Paola
Grandi
,
Emma J.
Jones
,
Bhumika
Karamshi
,
Kelly
Locke
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Simon C. C.
Lucas
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Anne-marie
Michon
,
Darren J.
Mitchell
,
Peter
Pogány
,
Rab K.
Prinjha
,
Christina
Rau
,
Ana Maria
Roa
,
Andrew D.
Roberts
,
Robert J.
Sheppard
,
Robert J.
Watson
Abstract: The bromodomain of ATAD2 has proved to be one of the least-tractable proteins within this target class. Here, we describe the discovery of a new class of inhibitors by high-throughput screening and show how the difficulties encountered in establishing a screening triage capable of finding progressible hits were overcome by data-driven optimization. Despite the prevalence of nonspecific hits and an exceptionally low progressible hit rate (0.001%), our optimized hit qualification strategy employing orthogonal biophysical methods enabled us to identify a single active series. The compounds have a novel ATAD2 binding mode with noncanonical features including the displacement of all conserved water molecules within the active site and a halogen-bonding interaction. In addition to reporting this new series and preliminary structure–activity relationship, we demonstrate the value of diversity screening to complement the knowledge-based approach used in our previous ATAD2 work. We also exemplify tactics that can increase the chance of success when seeking new chemical starting points for novel and less-tractable targets.
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Aug 2019
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B18-Core EXAFS
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Diamond Proposal Number(s):
[15151]
Abstract: Porous Organic Cages (POCs) are an emerging class of self-assembling, porous materials with novel properties. They offer a key advantage over other porous materials in permitting facile solution processing and re-assembly. The combination of POCs with metal nanoparticles (NPs) unlocks applications in the area of catalysis. In this context, POCs can function as both the template of ultra-small NPs and a porous, but reprocessable, heterogeneous catalyst support. Here, we demonstrate the synthesis of ultra-small Pd NPs with an imine linked POC known as ‘CC3’, and show that hydrogen gas can be used to form metallic NPs at ∼200 °C without the reduction of the organic cage (and the accompanying, unwanted loss of crystallinity). The resulting materials are characterized using a range of techniques (including powder diffraction, scanning transmission electron microscopy and synchrotron X-ray absorption spectroscopy) and shown to be recrystallizable following dissolution in organic solvent. Their catalytic efficacy is demonstrated using the widely studied carbon monoxide oxidation reaction. This demonstration paves the way for using ultra-small NPs synthesized with POCs as solution-processable, self-assembling porous catalytic materials.
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Aug 2019
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I19-Small Molecule Single Crystal Diffraction
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Wei
Zhang
,
Yong
Hua
,
Linqin
Wang
,
Biaobiao
Zhang
,
Yuanyuan
Liu
,
Peng
Liu
,
Valentina
Leandri
,
Yu
Guo
,
Hong
Chen
,
James M.
Gardner
,
Licheng
Sun
,
Lars
Kloo
Diamond Proposal Number(s):
[15819, 20805]
Abstract: Two zinc-based coordination complexes Y3 and Y4 have been synthesized, characterized and their performance as hole-transport materials (HTMs) for perovskite solar cells (PSCs) have been investigated. The complex Y3 contains two separate ligands, and the molecular structure can be seen as a dis-connected porphyrin ring. On the other hand, Y4 consists of a porphyrin core, and therefore a more extended conjugated system as compared to Y3. The optical and redox properties of the two different molecular complexes are comparable. However, the hole-mobility and conductivity of Y4 as macroscopic material are remarkably higher than that of Y3. Furthermore, when employed as hole-transport materials in perovskite solar cells, cells containing Y4 show a power conversion efficiency (PCE) of 16.05%, comparable to the Spiro-OMeTAD based solar cells with an efficiency around 17.08%. In contrast, solar cells based on Y3 show a negligible efficiency of about 0.01%. The difference in performance of Y3 and Y4 are analyzed and can be attributed to the difference in packing of the non-planar and planar building blocks in the corresponding materials.
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Aug 2019
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I03-Macromolecular Crystallography
I04-1-Macromolecular Crystallography (fixed wavelength)
I04-Macromolecular Crystallography
I24-Microfocus Macromolecular Crystallography
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Lucile
Moynie
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Stefan
Milenkovic
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Gaëtan L. A.
Mislin
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Véronique
Gasser
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Giuliano
Malloci
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Etienne
Baco
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Rory P.
Mccaughan
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Malcolm G. P.
Page
,
Isabelle J.
Schalk
,
Matteo
Ceccarelli
,
James H.
Naismith
Open Access
Abstract: Bacteria use small molecules called siderophores to scavenge iron. Siderophore-Fe3+ complexes are recognised by outer-membrane transporters and imported into the periplasm in a process dependent on the inner-membrane protein TonB. The siderophore enterobactin is secreted by members of the family Enterobacteriaceae, but many other bacteria including Pseudomonas species can use it. Here, we show that the Pseudomonas transporter PfeA recognises enterobactin using extracellular loops distant from the pore. The relevance of this site is supported by in vivo and in vitro analyses. We suggest there is a second binding site deeper inside the structure and propose that correlated changes in hydrogen bonds link binding-induced structural re-arrangements to the structural adjustment of the periplasmic TonB-binding motif.
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Aug 2019
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Open Access
Abstract: A mild, reductive spirocyclization of indole-linked amides and lactams for the efficient and selective synthesis of aza-spirocyclic indoline products is described. The catalytic reductive activation of tertiary amides or lactams by Vaska’s complex with tetramethyldisiloxane as the terminal reductant allowed iminium ion formation, before a diastereoselective 5-endo-trig spirocyclization of the tethered indole moiety was triggered. Terminal reduction affords the aza-spiroindoline products in an overall highly chemoselective and diastereoselective one-pot process.
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Aug 2019
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[16139]
Abstract: The solid form screening of galunisertib produced many solvates, prompting an extensive investigation into possible risks to the development of the favored monohydrate form. Inspired by crystal structure prediction, the search for neat polymorphs was expanded to an unusual range of experiments, including melt crystallization under pressure, to work around solvate formation and the thermal instability of the molecule. Ten polymorphs of galunisertib were found, however, the structure predicted to be the most stable has yet to be obtained. We present the crystal structures of all 10 unsolvated polymorphs of galunisertib, showing how state-of-the-art characterization methods can be combined with emerging computational modelling techniques to produce a complete structure landscape and assess the risk of late appearing, more stable polymorphs. The exceptional conformational polymorphism of this prolific solvate former invites further development of methods, computational and experimental, that are applicable to larger, flexible molecules with complex solid form landscapes.
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Aug 2019
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I24-Microfocus Macromolecular Crystallography
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Open Access
Abstract: Macromolecular Crystallography is a powerful and valuable technique to assess protein structures. Samples are commonly cryogenically cooled to minimise radiation damage effects from the X-ray beam, but low temperatures hinder normal protein functions and this procedure can introduce structural artefacts. Previous experiments utilising acoustic levitation for beamline science have focused on Langevin horns which deliver significant power to the confined droplet and are complex to set up accurately. In this work, the low power, portable TinyLev acoustic levitation system is used in combination with an approach to dispense and contain droplets, free of physical sample support to aid protein crystallography experiments. This method facilitates efficient X-ray data acquisition in ambient conditions compatible with dynamic studies. Levitated samples remain free of interference from fixed sample mounts, receive negligible heating, do not suffer significant evaporation and since the system occupies a small volume, can be readily installed at other light sources.
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Aug 2019
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B18-Core EXAFS
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Noam
Ralbag
,
Meirav
Mann-lahav
,
Elena S.
Davydova
,
Uri
Ash
,
Reuven
Galed
,
Michael
Handl
,
Renate
Hiesgen
,
Emanuele
Magliocca
,
William
Mustain
,
Jin
He
,
Peixi
Cong
,
Andrew
Beale
,
Gideon S.
Grader
,
David
Avnir
,
Dario R.
Dekel
Diamond Proposal Number(s):
[18835]
Abstract: In this work, we develop a new type of composite material that combines both electrocatalytic and ionic properties, by doping a silver metal catalyst with an anion-conducting ionomer at the molecular level. We show that ionomer entrapment into the silver metallic structure is possible, imparting unique properties to the catalytic character of the metallic silver. The novel composite material is tested as the cathode electrode of fuel cells, showing significant improvement in cell performance as compared with the undoped counterpart. This new type of material may then replace the current design of electrodes in advanced fuel cells or other electrochemical devices. The possibility to merge different properties into one composite material by molecular entrapment in metals can open the way to new materials, leading to unexplored fields and applications.
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Aug 2019
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