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13 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I19-Small Molecule Single Crystal Diffraction	High Pressure Crystal Structure and Electrical Properties of a Single Component Molecular Crystal [Ni(dddt)2] (dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate) Hengbo Cui , Takao Tsumuraya , Hamish H.-m. Yeung , Chloe S. Coates , Mark R. Warren , Reizo Kato Molecules 24 DOI: 10.3390/molecules24101843 Diamond Proposal Number(s): [15000] Open Access Show Abstract ▼ Abstract: Single-component molecular conductors form an important class of materials showing exotic quantum phenomena, owing to the range of behavior they exhibit under physical stimuli. We report the effect of high pressure on the electrical properties and crystal structure of the single-component crystal [Ni(dddt)2] (where dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate). The system is isoelectronic and isostructural with [Pd(dddt)2], which is the first example of a single-component molecular crystal that exhibits nodal line semimetallic behavior under high pressure. Systematic high pressure four-probe electrical resistivity measurements were performed up to 21.6 GPa, using a Diamond Anvil Cell (DAC), and high pressure single crystal synchrotron X-ray diffraction was performed up to 11.2 GPa. We found that [Ni(dddt)2] initially exhibits a decrease of resistivity upon increasing pressure but, unlike [Pd(dddt)2], it shows pressure-independent semiconductivity above 9.5 GPa. This correlates with decreasing changes in the unit cell parameters and intermolecular interactions, most notably the π-π stacking distance within chains of [Ni(dddt)2] molecules. Using first-principles density functional theory (DFT) calculations, based on the experimentally-determined crystal structures, we confirm that the band gap decreases with increasing pressure. Thus, we have been able to rationalize the electrical behavior of [Ni(dddt)2] in the pressure-dependent regime, and suggest possible explanations for its pressure-independent behavior at higher pressures.	May 2019
I12-JEEP: Joint Engineering, Environmental and Processing	Control of metal-organic framework crystallization by metastable intermediate pre-equilibrium species Hamish Yeung , Adam F. Sapnik , Felicity Massingberd-mundy , Michael W. Gaultois , Yue Wu , Duncan X. Fraser , Sebastian Henke , Roman Pallach , Niclas Heidenreich , Oxana Magdysyuk , Nghia T. Vo , Andrew L. Goodwin Angewandte Chemie International Edition DOI: 10.1002/anie.201810039 Diamond Proposal Number(s): [16354, 16450] Show Abstract ▼ Abstract: There is an increasingly large amount of interest in metal‐organic frameworks (MOFs) for a variety of applications, from gas sensing and separations to electronics and catalysis. Their exciting properties arise from their modular architectures, which self‐assemble from different combinations of metal‐based and organic building units. However, the exact mechanisms by which they crystallize remain poorly understood, thus limiting any realisation of real “structure by design”. We report important new insight into MOF formation, gained using in situ X‐ray diffraction, pH and turbidity measurements to uncover for the first time the evolution of metastable intermediate species in the canonical zeolitic imidazolate framework system, ZIF‐8. We reveal that the intermediate species exist in a dynamic pre‐equilibrium prior to network assembly and, depending on the reactant concentrations and the progress of reaction, the pre‐equilibrium can be made to favour under‐ or over‐coordinated Zn‐imidazolate species, thus accelerating or inhibiting crystallization, respectively. We thereby find that concentration can be effectively used as a synthetic handle to directly control particle size, with great implications for industrial scale‐up and gas sorption applications. These finding enables us to rationalise the apparent contradictions between previous studies of ZIF‐8 and, importantly, opens up new opportunities for the control of crystallization in network solids more generally, from the design of local structure to assembly of particles with precise dimensions.	Nov 2018
I11-High Resolution Powder Diffraction	Compositional inhomogeneity and tuneable thermal expansion in mixed-metal ZIF-8 analogues Adam F. Sapnik , Harry S. Geddes , Emily M. Reynolds , Hamish H.-m. Yeung , Andrew L. Goodwin Chemical Communications 13 DOI: 10.1039/C8CC04172E Diamond Proposal Number(s): [13284] Show Abstract ▼ Abstract: We study the structural and thermomechanical effects of cation substitution in the compositional family of metal–organic frameworks Zn1−xCdx(mIm)2 (HmIm = 2-methylimidazole). We find complete miscibility for all compositions x, with evidence of inhomogeneous distributions of Cd and Zn that in turn affect framework aperture characteristics. Using variable-temperature X-ray powder diffraction measurements, we show that Cd substitution drives a threefold reduction in the magnitude of thermal expansion behaviour. We interpret this effect in terms of an increased density of negative thermal expansion modes in the more flexible Cd-rich frameworks.	Aug 2018
I19-Small Molecule Single Crystal Diffraction	Hidden negative linear compressibility in lithium l-tartrate Hamish H.-m. Yeung , Rebecca Kilmurray , Claire Hobday , Scott C. Mckellar , Anthony K. Cheetham , David R. Allan , Stephen A. Moggach Phys. Chem. Chem. Phys. DOI: 10.1039/C6CP08690J Diamond Proposal Number(s): [9700] Show Abstract ▼ Abstract: By decoupling the mechanical behaviour of building units for the first time in a wine-rack framework containing two different strut types, we show that lithium l-tartrate exhibits NLC with a maximum value, Kmax = -21 TPa-1, and an overall NLC capacity, ΧNLC = 5.1 %, that are comparable to the most exceptional materials to date. Furthermore, the contributions from molecular strut compression and angle opening interplay to give rise to so-called “hidden” negative linear compressibility, in which NLC is absent at ambient pressure, switched on at 2 GPa and sustained up to the limit of our experiment, 5.5 GPa. Analysis of the changes in crystal structure using variable-pressure synchrotron X-ray diffraction reveals new chemical and geometrical design rules to assist the discovery of other materials with exciting hidden anomalous mechanical properties.	Jan 2017
I12-JEEP: Joint Engineering, Environmental and Processing	In Situ Observation of Successive Crystallizations and Metastable Intermediates in the Formation of Metal-Organic Frameworks Hamish Yeung , Yue Wu , Sebastian Henke , Anthony K. Cheetham , Dermot O' Hare , Richard Walton Angewandte Chemie International Edition 55, 2012 - 2016 DOI: 10.1002/anie.201508763 Diamond Proposal Number(s): [9661] Show Abstract ▼ Abstract: Understanding the driving forces controlling crys-tallization is essential for the efficient synthesis and design ofnew materials,particularly metal–organic frameworks(MOFs), where mild solvothermal synthesis often allowsaccess to various phases from the same reagents.Using high-energy in situ synchrotron X-ray powder diffraction, wemonitor the crystallization of lithium tartrate MOFs,observingthe successive crystallization and dissolution of three compet-ing phases in one reaction. By determining rate constants andactivation energies,wefully quantify the reaction energylandscape,gaining important predictive power for the choice ofreaction conditions.Different reaction rates are explained bythe structural relationships between the products and thereactants;larger changes in conformation result in higheractivation energies.The methods we demonstrate can easily beapplied to other materials,opening the door to agreaterunderstanding of crystallization in general.	Feb 2016
I19-Small Molecule Single Crystal Diffraction	Mechanical Properties of a Calcium Dietary Supplement, Calcium Fumarate Trihydrate Shijing Sun , Sebastian Henke , Michael T. Wharmby , Hamish H. M. Yeung , Wei Li , Anthony K. Cheetham Inorganic Chemistry 54 (23), 11186 - 11192 DOI: 10.1021/acs.inorgchem.5b01466 PMID: 26588472 Diamond Proposal Number(s): [8580] Show Abstract ▼ Abstract: The mechanical properties of calcium fumarate trihydrate, a 1D coordination polymer considered for use as a calcium source for food and beverage enrichment, have been determined via nanoindentation and high-pressure X-ray diffraction with single crystals. The nanoindentation studies reveal that the elastic modulus (16.7–33.4 GPa, depending on crystallographic orientation), hardness (1.05–1.36 GPa), yield stress (0.70–0.90 GPa), and creep behavior (0.8–5.8 nm/s) can be rationalized in view of the anisotropic crystal structure; factors include the directionality of the inorganic Ca–O–Ca chain and hydrogen bonding, as well as the orientation of the fumarate ligands. High-pressure single-crystal X-ray diffraction studies show a bulk modulus of ∼20 GPa, which is indicative of elastic recovery intermediate between small molecule drug crystals and inorganic pharmaceutical ingredients. The combined use of nanoindentation and high-pressure X-ray diffraction techniques provides a complementary experimental approach for probing the critical mechanical properties related to tableting of these dietary supplements.	Nov 2015
I15-Extreme Conditions I22-Small angle scattering & Diffraction	Hybrid glasses from strong and fragile metal-organic framework liquids Thomas Bennett , Jin-chong Tan , Yuanzheng Yue , Emma Baxter , Caterina Ducati , Nicholas Terrill , Hamish Yeung , Zhongfu Zhou , Wenlin Chen , Sebastian Henke , Anthony K. Cheetham , Neville Greaves Nature Communications 6 DOI: 10.1038/ncomms9079 PMID: 26314784 Diamond Proposal Number(s): [9691, 5692] Open Access Show Abstract ▼ Abstract: Hybrid glasses connect the emerging field of metal-organic frameworks (MOFs) with the glass formation, amorphization and melting processes of these chemically versatile systems. Though inorganic zeolites collapse around the glass transition and melt at higher temperatures, the relationship between amorphization and melting has so far not been investigated. Here we show how heating MOFs of zeolitic topology first results in a low density /`perfect/' glass, similar to those formed in ice, silicon and disaccharides. This order-order transition leads to a super-strong liquid of low fragility that dynamically controls collapse, before a subsequent order-disorder transition, which creates a more fragile high-density liquid. After crystallization to a dense phase, which can be remelted, subsequent quenching results in a bulk glass, virtually identical to the high-density phase. We provide evidence that the wide-ranging melting temperatures of zeolitic MOFs are related to their network topologies and opens up the possibility of /`melt-casting/' MOF glasses.	Aug 2015
I19-Small Molecule Single Crystal Diffraction	Mechanical Tunability via Hydrogen Bonding in Metal-Organic Frameworks with the Perovskite Architecture Wei Li , A. Thirumurugan , Phillip T. Barton , Zheshuai Lin , Sebastian Henke , Hamish Yeung , Michael Wharmby , Erica G. Bithell , Christopher J. Howard , Anthony K. Cheetham Journal Of The American Chemical Society 136 (22), 7801 - 7804 DOI: 10.1021/ja500618z Diamond Proposal Number(s): [8580] Show Abstract ▼ Abstract: Two analogous metal organic frameworks (MOFs) with the perovskite architecture, [C(NH2)3][Mn(HCOO)3] (1) and [(CH2)3NH2][Mn(HCOO)3] (2), exhibit significantly different mechanical properties. The marked difference is attributed to their distinct modes of hydrogen bonding between the A-site amine cation and the anionic framework. The stronger cross-linking hydrogen bonding in 1 gives rise to Young's moduli and hardnesses that are up to twice those in 2, while the thermal expansion is substantially smaller. This study presents clear evidence that the mechanical properties of MOF materials can be substantially tuned via hydrogen-bonding interactions.	Jun 2014
I11-High Resolution Powder Diffraction	Ligand-Directed Control over Crystal Structures of Inorganic-Organic Frameworks and Formation of Solid Solutions Hamish H.-m. Yeung , Wei Li , Paul J. Saines , Thomas K. J. Köster , Clare P. Grey , Anthony K. Cheetham Angewandte Chemie 125 (21), 5654 - 5657 DOI: 10.1002/ange.201300440 Show Abstract ▼ Abstract: Inorganic–organic frameworks with 3D Li–O–Li connectivity can form solid solutions through mechanochemical synthesis. High-resolution synchrotron powder X-ray diffraction and cross-polarization solid-state NMR spectroscopy demonstrate complete ligand mixing in the resulting binary and ternary systems (see picture for trends in unit cell volume (V) of the ternary system {Li2(suc)x(mal)y(met)z}n).	May 2013
I11-High Resolution Powder Diffraction	Ligand-Directed Control over Crystal Structures of Inorganic-Organic Frameworks and Formation of Solid Solutions Hamish Yeung , Li Wei Li , Paul Saines , Thomas K. J. Köster , Clare P. Grey , Anthony Cheetham Angewandte Chemie International Edition DOI: 10.1002/anie.201300440 PMID: 23533136 Show Abstract ▼ Abstract: Inorganic–organic frameworks with 3D Li–O–Li connectivity can form solid solutions through mechanochemical synthesis. High-resolution synchrotron powder X-ray diffraction and cross-polarization solid-state NMR spectroscopy demonstrate complete ligand mixing in the resulting binary and ternary systems (see picture for trends in unit cell volume (V) of the ternary system {Li2(suc)x(mal)y(met)z}n).	Mar 2013

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