Structure and Dynamics of the Superprotonic Conductor Caesium Hydrogen Sulfate, CsHSO.

We have investigated caesium hydrogen sulfate, CsHSO, in all three of its ambient pressure phases by total scattering neutron diffraction, inelastic neutron scattering (INS) and Raman spectroscopies and periodic density functional theory calculations. Above 140 °C, CsHSO, undergoes a phase transition to a superprotonic conductor that has potential application in intermediate temperature fuel cells. Total scattering neutron diffraction data clearly show that all the existing structures of this phase are unable to describe the local structure, because they have either partial occupancies of the atoms and/or non-physical O-H distances.

Hydrophilic and hydrophobic interactions in concentrated aqueous imidazole solutions: a neutron diffraction and total X-ray scattering study.

The intermolecular interactions in concentrated (5 M) aqueous imidazole solutions have been investigated by combining neutron diffraction with isotopic substitution, total X-ray scattering and empirical potential structure refinement (EPSR) simulations using a box containing 5530 water and 500 imidazole molecules. The structural model with the best fit was used to generate radial distribution functions and spatial density functions. The local volume surrounding imidazole molecules is dominated by water, due to strong hydrogen-bonding between the nitrogen moieties of imidazole and water molecules; within a radius of 6.

The effect of particle size, morphology and support on the formation of palladium hydride in commercial catalysts.

The relative amounts of hydrogen retained by a range of supported palladium catalysts have been investigated by a combination of electron microscopy and spectroscopic techniques, including incoherent inelastic neutron scattering. Contrary to expectation, the hydrogen capacity is not determined solely by the metal particle size, but it is a complex interaction between the particle size and its state of aggregation. The nature of the support is not only integral to the amount of hydrogen held by the catalyst, it also causes a marked difference in the rate of release of stored hydrogen from palladium.

A comparison of choline:urea and choline:oxalic acid deep eutectic solvents at 338 K.

1:2 choline chloride:urea and 1:1 choline chloride:oxalic acid deep eutectic solvents are compared at 338 K using liquid-phase neutron diffraction with H/D isotopic substitution to obtain differential neutron scattering cross sections and fitting of models to the experimental data using Empirical Potential Structure Refinement. In comparison to the previously reported study of choline chloride:urea at 303 K, we observed significant weakening and lengthening of choline-OH⋯Cl and choline-OH⋯hydrogen-bond acceptor correlations.

Dihydrogen vs. hydrogen bonding in the solvation of ammonia borane by tetrahydrofuran and liquid ammonia.

The solvation structures of two systems rich in hydrogen and dihydrogen bonding interactions have been studied in detail experimentally through neutron diffraction with hydrogen/deuterium isotopic substitution. The results were analysed by an atomistic Monte Carlo simulation employing refinement to the experimental scattering data. The systems studied were the hydrogen storage material ammonia borane (NH3BH3, AB) dissolved in tetrahydrofuran (THF), and liquid ammonia (NH3), the latter in which AB shows unusually high solubility (260 g AB per 100 g NH3) and potential regeneration properties.

Structures of a Clathrate Hydrate Former, Inhibitor, and Synergist in Water.

SANS studies are reported for aqueous THF at the 1:17 clathrate hydrate-forming composition and on aqueous solutions of the synergist 2-butoxyethanol. Addition of the clathrate hydrate inhibitor polyvinylcaprolactam and a dimeric model compound, 1,3-bis(caprolactamyl)butane, show that the inhibitors do not significantly affect the solution structures of these two important species in clathrate hydrate formation and inhibition. The SANS studies show that 1,3-bis(caprolactamyl)butane is a good model for polyvinylcaprolactam, and both the polymer and model compound exhibit hydrogen bonding interactions with water but do not interact significantly with 2-butoxyethanol in aqueous solution.

Confinement of Iodine Molecules into Triple-Helical Chains within Robust Metal-Organic Frameworks.

During nuclear waste disposal process, radioactive iodine as a fission product can be released. The widespread implementation of sustainable nuclear energy thus requires the development of efficient iodine stores that have simultaneously high capacity, stability and more importantly, storage density (and hence minimized system volume). Here, we report high I adsorption in a series of robust porous metal-organic materials, MFM-300(M) (M = Al, Sc, Fe, In).

On the structure of an aqueous propylene glycol solution.

Using a combination of neutron diffraction and empirical potential structure refinement computational modelling, the interactions in a 30 mol. % aqueous solution of propylene glycol (PG), which govern both the hydration and association of this molecule in solution, have been assessed. From this work it appears that PG is readily hydrated, where the most prevalent hydration interactions were found to be through both the PG hydroxyl groups but also alkyl groups typically considered hydrophobic.

The reaction of formic acid with Raney copper.

The interaction of formic acid with Raney Cu proves to be complex. Rather than the expected generation of a monolayer of bidentate formate, we find the formation of a Cu(II) compound. This process occurs by direct reaction of copper and formic acid; in contrast, previous methods are by solution reaction.

Dissolved chloride markedly changes the nanostructure of the protic ionic liquids propylammonium and ethanolammonium nitrate.

The bulk nanostructure of 15 mol% propylammonium chloride (PACl) dissolved in propylammonium nitrate (PAN) and 15 mol% ethanolammonium chloride (EtACl) in ethanolammonium nitrate (EtAN) has been determined using neutron diffraction with empirical potential structure refinement fits. For both the PAN:PACl and EtAN:EtACl mixtures, data for three different scattering contrasts were simultaneously fit, and the structures determined and compared to that of the pure ionic liquids. Strong electrostatic interactions between chloride and cation charged groups, as well as the alcohol moiety of EtAN, lead to marked changes in local ion packing that alter the liquid structure.

On the atomic structure of cocaine in solution.

Cocaine is an amphiphilic drug which has the ability to cross the blood-brain barrier (BBB). Here, a combination of neutron diffraction and computation has been used to investigate the atomic scale structure of cocaine in aqueous solutions. Both the observed conformation and hydration of cocaine appear to contribute to its ability to cross hydrophobic layers afforded by the BBB, as the average conformation yields a structure which might allow cocaine to shield its hydrophilic regions from a lipophilic environment.

Structure and spectroscopy of CuH prepared via borohydride reduction.

Copper(I) hydride (cuprous hydride, CuH) was the first binary metal hydride to be discovered (in 1844) and is singular in that it is synthesized in solution, at ambient temperature. There are several synthetic paths to CuH, one of which involves reduction of an aqueous solution of CuSO4·5H2O by borohydride ions. The product from this procedure has not been extensively characterized.

How the surface structure determines the properties of CuH.

CuH is a material that appears in a wide diversity of circumstances ranging from catalysis to electrochemistry to organic synthesis. There are both aqueous and nonaqueous synthetic routes to CuH, each of which apparently leads to a different product. We developed synthetic methodologies that enable multigram quantities of CuH to be produced by both routes and characterized each product by a combination of spectroscopic, diffraction and computational methods.

Association and liquid structure of pyridine-acetic acid mixtures determined from neutron scattering using a 'free proton' EPSR simulation model.

The liquid structure of pyridine-acetic acid mixtures have been investigated using neutron scattering at various mole fractions of acetic acid, χHOAc = 0.33, 0.50, and 0.

Supramolecular binding and separation of hydrocarbons within a functionalized porous metal-organic framework.

Supramolecular interactions are fundamental to host-guest binding in many chemical and biological processes. Direct visualization of such supramolecular interactions within host-guest systems is extremely challenging, but crucial to understanding their function. We report a comprehensive study that combines neutron scattering, synchrotron X-ray and neutron diffraction, and computational modelling to define the detailed binding at a molecular level of acetylene, ethylene and ethane within the porous host NOTT-300.

Conformation and interactions of dopamine hydrochloride in solution.

The aqueous solution of dopamine hydrochloride has been investigated using neutron and X-ray total scattering data together with Monte-Carlo based modelling using Empirical Potential Structure Refinement. The conformation of the protonated dopamine molecule is presented and the results compared to the conformations found in crystal structures, dopamine-complexed protein crystal structures and predicted from theoretical calculations and pharmacophoric models. It is found that protonated dopamine adopts a range of conformations in solution, highlighting the low rotational energy barrier between different conformations, with the preferred conformation being trans-perpendicular.

Understanding composition-property relationships in Ti-Cr-V-Mo alloys for optimisation of hydrogen storage in pressurised tanks.

The location of hydrogen within Ti-Cr-V-Mo alloys has been investigated during hydrogen absorption and desorption using in situ neutron powder diffraction and inelastic neutron scattering. Neutron powder diffraction identifies a low hydrogen equilibration pressure body-centred tetragonal phase that undergoes a martensitic phase transition to a face-centred cubic phase at high hydrogen equilibration pressures. The average location of the hydrogen in each phase has been identified from the neutron powder diffraction data although inelastic neutron scattering combined with density functional theory calculations show that the local structure is more complex than it appears from the average structure.

Hydrogen production from ammonia using sodium amide.

This paper presents a new type of process for the cracking of ammonia (NH3) that is an alternative to the use of rare or transition metal catalysts. Effecting the decomposition of NH3 using the concurrent stoichiometric decomposition and regeneration of sodium amide (NaNH2) via sodium metal (Na), this represents a significant departure in reaction mechanism compared with traditional surface catalysts. In variable-temperature NH3 decomposition experiments, using a simple flow reactor, the Na/NaNH2 system shows superior performance to supported nickel and ruthenium catalysts, reaching 99.

In situ X-ray powder diffraction studies of hydrogen storage and release in the Li-N-H system.

We report the experimental investigation of hydrogen storage and release in the lithium amide-lithium hydride composite (Li-N-H) system. Investigation of hydrogenation and dehydrogenation reactions of the system through in situ synchrotron X-ray powder diffraction experiments allowed for the observation of the formation and evolution of non-stoichiometric intermediate species of the form Li1+xNH2-x. This result is consistent with the proposed Frenkel-defect mechanism for these reactions.

Selectivity and direct visualization of carbon dioxide and sulfur dioxide in a decorated porous host.

Understanding the mechanism by which porous solids trap harmful gases such as CO(2) and SO(2) is essential for the design of new materials for their selective removal. Materials functionalized with amine groups dominate this field, largely because of their potential to form carbamates through H(2)N(δ(-))···C(δ(+))O(2) interactions, thereby trapping CO(2) covalently. However, the use of these materials is energy-intensive, with significant environmental impact.

Chiral Ag(I) and Pt(II) complexes of ditopic NHC ligands: synthesis, structural and spectroscopic properties.

The butyl and isopropyl derivatives (4I, 5Br) of chiral pool derived bis-imidazolium dehydrohexitol salts have been prepared. The ditopic N-heterocyclic carbenes 4 and 5 form dinuclear Ag(I) and Pt(II) complexes. All compounds were fully characterised by multinuclear NMR spectroscopy.

Two new cluster ions, Ga[GaH3]4(5-) with a neopentane structure in Rb8Ga5H15 and [GaH2]n(n-) with a polyethylene structure in Rb(n)(GaH2)n, represent a new class of compounds with direct Ga-Ga bonds mimicking common hydrocarbons.

The first examples of a new class of gallium hydride clusters with direct Ga-Ga bonds and common hydrocarbon structures are reported. Neutron powder diffraction was used to find a Ga[GaH(3)](4)(5-) cluster ion with a neopentane structure in a novel cubic structure type of Rb(8)Ga(5)H(15). Another cluster ion with a polyethylene structure, [GaH(2)](n)(n-), was found in a second novel (RbGaH(2))(n) hydride.

Synthesis and evaluation of metallocene containing methylidene-1,3-dihydro-2H-indol-2-ones as kinase inhibitors.

(E)- and (Z)-3-Ferrocenylmethylidene-1,3-dihydro-2H-indol-2-ones 1 have been structurally modified in order to explore SAR against a range of kinases. Of note is the submicromolar to low micromolar inhibition of DYRK3 and 4 by a number of complexes. Screening using Xenopus embryos showed some of the compounds to have potent antiangiogenisis activity.

Microwave-mediated synthesis of an arylboronate library.

A series of arylboronates has been synthesized from the reaction of 2-(2-, (3-, or (4-(bromomethyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 1{1-3} respectively with a range of N-, S-, and O-nucleophiles, using microwave-mediated chemistry. For the synthesis of N- and S-substituted boronates, a supported base, PS-NMM, was employed, and many reactions were complete within 15 min. With O-nucleophiles, a mixture of tetrabutylammonium bromide, potassium carbonate, and sodium hydroxide was employed.

Pore with gate: modulating hydrogen storage in metal-organic framework materials via cation exchange.

A range of anionic metal-organic framework (MOF) materials has been prepared by combination of In(III) with tetracarboxylate isophthalate-based ligands. These materials incorporate organic cations, either H2ppz2+ (ppz = piperazine) or Me2NH2+, that are hydrogen bonded to the pore wall. These cations act as a gate controlling entry of N2 and H2 gas into and out of the porous host.