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108 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I19-Small Molecule Single Crystal Diffraction	Enantioselective recognition of racemic amino alcohols in aqueous solution by chiral metal-oxide keplerate {Mo132}-cluster capsules Lee Cronin , Robert Pow , Zoe Sinclair , Nicola Bell , Nancy Watfa , Yousef Abul-Haija , Deliang Long Chemistry – A European Journal DOI: 10.1002/chem.202100899 Diamond Proposal Number(s): [18953] Open Access Show Abstract ▼ Abstract: Determining the relative configuration or enantiomeric excess of a substance may be achieved using NMR spectroscopy by employing chiral shift reagents (CSRs). Such reagents non-covalently interact with the chiral solute, resulting in each chiral form experiencing different magnetic anisotropy, which is reflected in their NMR spectra. The Keplerate polyoxometalate (POM) is a molybdenum-based, water-soluble, discrete inorganic structure with a pore-accessible inner cavity, decorated by differentiable ligands. Through ligand exchange from the self-assembled nanostructure we have synthesized a set of chiral Keplerate host molecules. By exploiting interactions of analyte molecules at the surface pores we establish the relative configuration of chiral amino alcohol guests (phenylalaninol and 2-amino-1-phenylethanol) in aqueous solvent and determine their enantiomeric excess by 1 H NMR. The use of POMs as chiral shift reagents represents an application of the class that is yet to be well established and opens avenues into aqueous host-guest chemistry with self-assembled recognition agents.	Jul 2021
I11-High Resolution Powder Diffraction	Cation ordering and exsolution in copper‐containing forms of the flexible zeolite Rho (Cu,M‐Rho; M = H, Na) and their consequences for CO2 adsorption Magdalena Lozinska , Sophie Jamieson , Maarten Verbraeken , David Miller , Bela Bode , Claire Murray , Stefano Brandani , Paul Anthony Wright Chemistry – A European Journal DOI: 10.1002/chem.202101664 Diamond Proposal Number(s): [22322] Show Abstract ▼ Abstract: The flexibility of the zeolite Rho framework offers great potential for tunable molecular sieving. The fully copper-exchanged form of Rho and mixed Cu,H- and Cu,Na-forms have been prepared. EPR spectroscopy reveals Cu 2+ cations are present in the dehydrated forms and Rietveld refinement shows these prefer S6R sites, away from the d8r windows that control diffusion. Fully exchanged Cu-Rho remains in an open form upon dehydration, the d8r windows remain nearly circular and the occupancy of window sites is low, so that it adsorbs CO 2 rapidly at room temperature. Breakthrough tests with 10% CO 2 /40% CH 4 mixtures show that Cu 4.9 -Rho is able to produce pure methane, albeit with a relatively low capacity at this p CO2 due to the weak interaction of CO 2 with Cu cations. This is in strong contrast with Na-Rho, where cations in narrow elliptical window sites enable CO 2 to be adsorbed with high selectivity and uptake but too slowly to enable the production of pure methane in similar breakthrough experiments. A series of Cu,Na-Rho materials was prepared to improve uptake and selectivity compared to Cu-Rho, and kinetics compared to Na-Rho. Remarkably, Cu,Na-Rho with >2 Cu cations per unit cell exhibited exsolution, due to the preference of Na cations for narrow S8R sites in distorted Rho and of Cu cations for S6R sites in the centric, open form of Rho. The exsolved Cu,Na-Rho showed improved performance in CO 2 /CH 4 breakthrough tests, producing pure CH 4 with improved uptake and CO 2 /CH 4 selectivity compared to that of Cu 4.9 -Rho.	Jul 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Monitoring the structure evolution of titanium oxide photocatalysts: From the molecular form via the amorphous state to the crystalline phase Ezgi Onur Sahin , Yitao Dai , Candace Chan , Harun Tuysuz , Wolfgang Schmidt , Joohyun Lim , Siyuan Zhang , Cristina Scheu , Claudia Weidenthaler Chemistry – A European Journal DOI: 10.1002/chem.202101117 Diamond Proposal Number(s): [12102] Show Abstract ▼ Abstract: Amorphous TixOy with high surface area has attracted significant interest as photocatalyst with higher activity in ultraviolet (UV) light-induced water splitting applications compared to commercial nanocrystalline TiO2. Under photocatalytic operation conditions, the structure of the molecular titanium alkoxide precursor rearranges upon hydrolysis and leads to higher connectivity of the structure-building units. Structurally ordered domains with sizes smaller than 7 Å form larger aggregates. The experimental scattering data can be explained best with a structure model consisting of an anatase-like core and a distorted shell. Upon exposure with UV light, the white TixOy suspension turns dark corresponding to the reduction of Ti 4+ to Ti 3+ as confirmed by electron energy loss spectroscopy (EELS). Heat-induced crystallisation was followed by in situ temperature-dependent total scattering experiments. First, ordering in the Ti-O environment takes place upon to 350 °C. Above this temperature, the distorted anatase core starts to grow but the structure obtained at 400 °C is still not fully ordered.	Jun 2021
B18-Core EXAFS E01-JEM ARM 200CF I11-High Resolution Powder Diffraction	Direct visualization of substitutional Li doping in supported Pt nanoparticles and their ultra-selective catalytic hydrogenation performance Tianyi Chen , Christopher Foo , Jianwei Zheng , Huihuang Fang , Peter Nellist , Edman Shik Chi Tsang Chemistry – A European Journal DOI: 10.1002/chem.202101470 Diamond Proposal Number(s): [20856] Show Abstract ▼ Abstract: It has only recently been established that doping light elements (lithium, boron, and carbon) into supported transition metals can fill interstitial sites, which can be observed by the expanded unit cell. As an example, interstitial lithium (intLi) can block H filling octahedral interstices of palladium metal lattice, which improves partial hydrogenation of alkynes to alkenes under hydrogen. In contrast, herein, we report intLi is not found in the case of Pt/C. Instead, we observe for the first time a direct ‘substitution’ of Pt with substitutional lithium (subLi) in alternating atomic columns using scanning transmission electron microscopy-annular dark field (STEM-ADF). This ordered substitutional doping results in a contraction of the unit cell as shown by high-quality synchrotron X-ray diffraction (SXRD). The electron donation of d-band of Pt without higher orbital hybridizations by subLi offers an alternative way for ultra-selectivity in catalytic hydrogenation of carbonyl compounds by suppressing the facile CO bond breakage that would form alcohols.	Jun 2021
I09-Surface and Interface Structural Analysis	Structural transformation of surface-confined porphyrin networks by addition of Co atoms Brian David Baker Cortés , Mihaela Enache , Kathrin Küster , Florian Studener , Tien-Lin Lee , Nicolas Marets , Véronique Bulach , Mir Wais Hosseini , Meike Stohr Chemistry – A European Journal DOI: 10.1002/chem.202101217 Diamond Proposal Number(s): [11841] Show Abstract ▼ Abstract: The self-assembly of a nickel-porphyrin derivative (Ni-DPPyP) containing two pyridyl coordinating sites and two pentyl chains at trans meso positions was studied with scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) on Au(111). Deposition of Ni-DPPyP onto Au(111) gave rise to a close-packed network for coverages smaller or equal to one monolayer as revealed by STM and LEED. The molecular arrangement of this two-dimensional network is stabilized via hydrogen bonds formed between the pyridyl’s nitrogen and hydrogen atoms from the pyrrole groups of neighboring molecules. Subsequent deposition of cobalt atoms onto the close-packed network and post-deposition annealing at 423 K led to the formation of a Co-coordinated hexagonal porous network. As confirmed by XPS measurements, the porous network is stabilized by metal-ligand interactions between one cobalt atom and three pyridyl ligands, each pyridyl ligand coming from a different Ni-DPPyP molecule.	Jun 2021
I04-Macromolecular Crystallography	The development of non‐hydrolysable oligosaccharide activity‐based inactivators for endoglycanases: A case study on a‐1,6 mannanases Hermen S. Overkleeft , Sybrin Schröder , Wendy Offen , Alexandra Males , Yi Jin , Casper De Boer , Jacopo Enotarpi , Gijs Van Der Marel , Bogdan Florea , Jeroen Codée , Gideon Davies Chemistry – A European Journal DOI: 10.1002/chem.202101255 Diamond Proposal Number(s): [13587, 18598] Show Abstract ▼ Abstract: There is a vast genomic resource for enzymes active on carbohydrates. Lagging far behind, however, are functional chemical tools for the rapid characterization of carbohydrate‐active enzymes. Activity‐based probes (ABPs) offer one chemical solution to these issues with ABPs based upon cyclophellitol epoxide and aziridine covalent and irreversible inhibitors representing a potent and widespread approach. Such inhibitors for enzymes active on polysaccharides are potentially limited by the requirement for several glycosidic bonds, themselves substrates for the enzyme targets. Here we show that non‐hydrolysable trisaccharide can be synthesized and applied even to enzymes with challenging subsite requirements. We find that incorporation of carbasugar moieties, which we accomplished by cuprate‐assisted regioselective trans‐diaxial epoxide opening of carba‐mannal we synthesised for this purpose, yields inactivators that act as powerful activity‐based inhibitors for a‐1,6 endo‐mannanases. 3‐D structures at 1.35 – 1.47 Å resolutions confirm the design rationale and binding to the enzymatic nucleophile. Carbasugar oligosaccharide cyclophellitols offer a powerful new approach for the design of robust endoglycosidase inhibitors, while the synthesis procedures presented here should allow adaptation towards activity‐based endoglycosidase probes as well as configurational isosteres targeting other endoglycosidase families.	Apr 2021
I11-High Resolution Powder Diffraction I19-Small Molecule Single Crystal Diffraction	Inherent ethyl acetate selectivity in a trianglimine molecular solid Donglin He , Chengxi Zhao , Linjiang Chen , Marc Little , Samantha Chong , Rob Clowes , Katherine Mckie , Mark Roper , Graeme Day , Ming Liu , Andrew Cooper Chemistry – A European Journal DOI: 10.1002/chem.202101510 Diamond Proposal Number(s): [21726, 17193] Show Abstract ▼ Abstract: Ethyl acetate is an important chemical raw material and solvent. It is also a key volatile organic compound in the brewing industry and a marker for lung cancer. Materials that are highly selective toward ethyl acetate are needed for its separation and detection. Here, we report a trianglimine macrocycle ( TAMC ) that selectively adsorbs ethyl acetate by forming a solvate. Crystal structure prediction showed this to be the lowest energy solvate structure available. This solvate leaves a metastable, ‘templated’ cavity after solvent removal. Adsorption and breakthrough experiments confirmed that imprinted TAMC has adequate adsorption kinetics to separate ethyl acetate from azeotropic mixtures with ethanol, which is a challenging and energy‐intensive industrial separation.	Apr 2021
I19-Small Molecule Single Crystal Diffraction	Controlled synthesis of large single crystals of metal‐organic framework CPO‐27‐Ni prepared by a modulation approach: in situ single crystal X‐ray diffraction studies Simon Maximilian Vornholt , Caroline Elliott , Cameron Rice , Samantha Russell , Peter J. Kerr , Daniel N. Rainer , Michal Mazur , Mark R. Warren , Paul S. Wheatley , Russell E. Morris Chemistry – A European Journal DOI: 10.1002/chem.202100528 Diamond Proposal Number(s): [24028] Open Access Show Abstract ▼ Abstract: The size of single crystals of the metal-organic framework CPO-27-Ni was incrementally increased through a series of modulated syntheses. A novel linker modulated synthesis using 2,5-dihydroxyterephthalic acid and the isomeric ligand 4,6-dihydroxyisophthalic acid yielded large single crystals of CPO-27-Ni (~70 µm). All materials proved high crystallinity and phase pure through powder X-ray diffraction, electron microscopy methods, thermogravimetric, and compositional analysis. For the first time single crystal structure analyses were carried out on CPO-27-Ni. High BET surface areas and nitric oxide (NO) release efficiencies were recorded for all materials. Large single crystals of CPO-27-Ni showed a prolonged NO release and proved suitable for in situ single crystal diffraction experiments to follow the NO adsorption. An efficient activation protocol was developed, leading to a dehydrated structure after just 4 h, which subsequently was NO-loaded, giving a first NO loaded single crystal structural model of CPO-27-Ni.	Mar 2021
	Surface engineering strategy using urea to improve the rate performance of Na2Ti3O7 in Na‐ion batteries Sara I. R. Costa , Yong‐seok Choi , Alistair J. Fielding , Andrew J. Naylor , John M. Griffin , Zdeněk Sofer , David O. Scanlon , Nuria Tapia-Ruiz Chemistry – A European Journal 27, 3875 - 3886 DOI: 10.1002/chem.v27.11 Open Access Show Abstract ▼ Abstract: Na2Ti3O7 (NTO) is considered a promising anode material for Na‐ion batteries due to its layered structure with an open framework and low and safe average operating voltage of 0.3 V vs. Na+/Na. However, its poor electronic conductivity needs to be addressed to make this material attractive for practical applications among other anode choices. Here, we report a safe, controllable and affordable method using urea that significantly improves the rate performance of NTO by producing surface defects such as oxygen vacancies and hydroxyl groups, and the secondary phase Na2Ti6O13. The enhanced electrochemical performance agrees with the higher Na+ ion diffusion coefficient, higher charge carrier density and reduced bandgap observed in these samples, without the need of nanosizing and/or complex synthetic strategies. A comprehensive study using a combination of diffraction, microscopic, spectroscopic and electrochemical techniques supported by computational studies based on DFT calculations, was carried out to understand the effects of this treatment on the surface, chemistry and electronic and charge storage properties of NTO. This study underscores the benefits of using urea as a strategy for enhancing the charge storage properties of NTO and thus, unfolding the potential of this material in practical energy storage applications.	Feb 2021
B18-Core EXAFS	Solvent‐dependent growth and stabilization mechanisms of surfactant‐free colloidal Pt nanoparticles Jonathan Quinson , Sarah Neumann , Laura Kacenauskaite , Jan Bucher , Jacob J. K. Kirkensgaard , Søren B. Simonsen , Luise Theil Kuhn , Alessandro Zana , Tom Vosch , Mehtap Oezaslan , Sebastian Kunz , Matthias Arenz Chemistry – A European Journal 26, 9012 - 9023 DOI: 10.1002/chem.202001553 Diamond Proposal Number(s): [12746] Show Abstract ▼ Abstract: Understanding the formation of nanoparticles (NPs) is key to develop materials by sustainable routes. The Co4CatTM process is a new synthesis of precious metal NPs in alkaline mono‐alcohols well‐suited to develop active nanocatalysts. The synthesis is ‘facile’, surfactant‐free and performed under mild conditions like low temperature. The reducing properties of the solvent are here shown to strongly influence the formation of Pt NPs. Based on the in situ formation of CO adsorbed on the NP surface by solvent oxidation, a model is proposed that accounts for the different growth and stabilization mechanisms as well as re‐dispersion properties of the surfactant‐free NPs in different solvents. Using in situ and ex situ characterizations, it is established that in methanol, a slow nucleation with a limited NP growth is achieved. In ethanol, a fast nucleation followed by continuous and pronounced particle sintering occurs.	Jul 2020

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