Direct observation of H\u3csub\u3e2\u3c/sub\u3e binding to a metal oxide surface

Inelastic neutron scattering is used to probe the dynamical response of H2 films adsorbed on MgO(100) as a function of film thickness. Concomitant diffraction measurements and a reduced-dimensionality quantum dynamical model provide insight into the molecule-surface interaction potential. At monolayer thickness, the rotational motion is strongly influenced by the surface, so that the molecules behave like quasiplanar rotors. These findings have a direct impact on understanding how molecular hydrogen binds to the surface of materials used in catalytic and storage applications

Сіверські князі Наримунтовичі

У статті досліджується генеалогія та діяльність сіверських Наримунтовичів – однієї з гілок литовсько-руської династії Гедиміновичів, представники якої наприкінці XIV – початку XV ст. володіли кількома удільними князівствами у Сіверській землі.В статье исследуется генеалогия и деятельность северских Наримунтовичей – одной из ветвей литовско-русской династии Гедиминовичей, представители которой в конце XIV – начале XV вв. владели несколькими удельными княжествами в Северской земле.The article deals with genealogy and activity of the seversky Narimuntoviches as one of branches of the Lithuanian-Russian dynasty of the Gediminoviches, representatives of which at the end XIV – beginning of XV centuries owned some specific principalities in the Seversky land

Hydrogen Dynamics in Lightweight Tetrahydroborates

The high hydrogen content in complex hydrides such as M[AlH4]x and M[BH4]x (M = Li, Na,K, Mg, Ca) stimulated many research activities to utilize them as hydrogen storage materials. An understanding of the dynamical properties on themolecular level is important to understand and to improve the sorption kinetics. Hydrogen dynamics in complex hydrides comprise long range translational diffusion as well as localized motions like vibrations, librations or rotations. All the different motions are characterized by their specific length- and timescales. Within this review we give an introduction to the physical properties of lightweight complex hydrides and illustrate the huge variety of dynamical phenomena on selected example

Comparing the use of ERA5 reanalysis dataset and ground-based agrometeorological data under different climates and topography in Italy

Study region: The study region is represented by seven irrigation districts distributed under different climate and topography conditions in Italy. Study focus: This study explores the reliability and consistency of the global ERA5 single levels and ERA5-Land reanalysis datasets in predicting the main agrometeorological estimates commonly used for crop water requirements calculation. In particular, the reanalysis data was compared, variable-by-variable (e.g., solar radiation, R-s; air temperature, T-air; relative humidity, RH; wind speed, u(10); reference evapotranspiration, ET0), with in situ agrometeorological obser-vations obtained from 66 automatic weather stations (2008-2020). In addition, the presence of a climate-dependency on their accuracy was assessed at the different irrigation districts. New hydrological insights for the region: A general good agreement was obtained between observed and reanalysis agrometeorological variables at both daily and seasonal scales. The best perfor-mance was obtained for T-air, followed by RH, R-s, and u(10) for both reanalysis datasets, especially under temperate climate conditions. These performances were translated into slightly higher accuracy of ET0 estimates by ERA5-Land product, confirming the potential of using reanalysis datasets as an alternative data source for retrieving the ET0 and overcoming the unavailability of observed agrometeorological data

Heterolytic Scission of Hydrogen Within a Crystalline Frustrated Lewis Pair

We report the heterolysis of molecular hydrogen under ambient conditions by the crystalline frustrated Lewis pair (FLP) 1-{2-[bis (pentafluorophenyOboryl] phenyl -2, 2,6,6-tetrame-thylpiperidine (KCAT). The gas-solid reaction provides an approach to prepare the solvent-free, polycrystalline ion pair KCATH2 through a single crystal to single crystal transformation. The crystal lattice of KCATH2 increases in size relative to the parent KCAT by approximately 2%. Microscopy was used to follow the transformation of the highly colored red/orange KCAT to the colorless KCATH2 over a period of 2 h at 300 K under a flow of H-2 gas. There is no evidence of crystal decrepitation during hydrogen uptake. Inelastic neutron scattering employed over a temperature range from 4-200 K did not provide evidence for the formation of polarized H-2 in a precursor complex within the crystal at low temperatures and high pressures. However, at 300 K, the INS spectrum of KCAT transformed to the INS spectrum of KCATH2. Calculations suggest that the driving force is more favorable in the solid state compared to the solution or gas phase, but the addition of H-2 into the KCAT crystal is unfavorable. Ab Initio methods were used to calculate the INS spectra of KCAT, KCATH2, and a possible precursor complex of H-2 in the pocket between the B and N of crystalline KCAT. Ex-situ NMR showed that the transformation from KCAT to KCATH2 is quantitative and our results suggest that the hydrogen heterolysis process occurs via H-2 diffusion into the FLP crystal with a rate-limiting movement of H-2 from inactive positions to reactive sites.Peer reviewe

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

Supramolecular interactions are fundamental to host-guest binding in chemical and biological processes. Direct visualisation of such supramolecular interactions within host-guest systems is extremely challenging but crucial for the understanding of their function. We report a comprehensive study combining neutron scattering with synchrotron X-ray and neutron diffraction, coupled with computational modelling, to define the detailed binding at a molecular level of acetylene, ethylene and ethane within the porous host NOTT-300. This study reveals the simultaneous and cooperative hydrogen-bonding, π···π stacking interactions and inter-molecular dipole interactions in the binding of acetylene and ethylene to give up to twelve individual weak supramolecular interactions aligned within the host to form an optimal geometry for intelligent, selective binding of hydrocarbons. We also report, for the first time, the cooperative binding of a mixture of acetylene and ethylene within the porous host together with the corresponding breakthrough experiment and analysis of mixed gas adsorption isotherms

Methane hydrate formation in confined nanospace can surpass nature

Natural methane hydrates are believed to be the largest source of hydrocarbons on Earth. These structures are formed in specific locations such as deep-sea sediments and the permafrost based on demanding conditions of high pressure and low temperature. Here we report that, by taking advantage of the confinement effects on nanopore space, synthetic methane hydrates grow under mild conditions (3.5 MPa and 2 degrees C), with faster kinetics (within minutes) than nature, fully reversibly and with a nominal stoichiometry that mimics nature. The formation of the hydrate structures in nanospace and their similarity to natural hydrates is confirmed using inelastic neutron scattering experiments and synchrotron X-ray powder diffraction. These findings may be a step towards the application of a smart synthesis of methane hydrates in energy-demanding applications (for example, transportation).We acknowledge UK Science and Technlology Facilities Council for the provision of beam time on the TOSCA spectrometer (Projects RB1410624 and RB122099) and financial support from the European Commission under the 7th Framework Programme through the 'Research Infrastructures' action of the 'Capacities' Programme (NMI3-II Grant number 283883). J.S.-A. and F.R. acknowledges the financial support from MINECO: Strategic Japanese-Spanish Cooperation Program (PLE2009-0052), Concert Project-NASEMS (PCIN-2013-057) and Generalitat Valenciana (PROMETEO/2009/002). F.R. and J.L.J. thank the financial support from MINECO (MAT2012-38567-C02-01, Consolider Ingenio 2010-Multicat CSD-2009-00050 and SEV-2012-0267). K.K. thanks Grant-in-Aid for Scientific Research (A) (2424-1038), Japan. 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Refinement of pore size at sub-angstrom precision in robust metal-organic frameworks for separation of xylenes

The demand for xylenes is projected to increase over the coming decades. The separation of xylene isomers, particularly p- and m-xylenes, is vital for the production of numerous polymers and materials. However, current state-of-the-art separation is based upon fractional crystallisation at 220 K which is highly energy intensive. Here, we report the discrimination of xylene isomers via refinement of the pore size in a series of porous metal–organic frameworks, MFM-300, at sub-angstrom precision leading to the optimal kinetic separation of all three xylene isomers at room temperature. The exceptional performance of MFM-300 for xylene separation is confirmed by dynamic ternary breakthrough experiments. In-depth structural and vibrational investigations using synchrotron X-ray diffraction and terahertz spectroscopy define the underlying host–guest interactions that give rise to the observed selectivity (p-xylene < o-xylene < m-xylene) and separation factors of 4.6–18 for p- and m-xylenes