Trace benzene capture by decoration of structural defects in metal-organic framework materials.

Capture of trace benzene is an important and challenging task. Metal-organic framework materials are promising sorbents for a variety of gases, but their limited capacity towards benzene at low concentration remains unresolved. Here we report the adsorption of trace benzene by decorating a structural defect in MIL-125-defect with single-atom metal centres to afford MIL-125-X (X = Mn, Fe, Co, Ni, Cu, Zn; MIL-125, TiO(OH)(BDC) where HBDC is 1,4-benzenedicarboxylic acid).

Neutron Vibrational Spectroscopic Study of the Acetylene: Ammonia (1:1) Cocrystal Relevant to Titan, Saturn's Moon.

The surface of Titan, Saturn's icy moon, is believed to be composed of various molecular minerals with a great diversity in structure and composition. Under the surface conditions, 93 K and 1.45 atm, most small molecules solidify and form minerals, including acetylene and ammonia.

Binding of carbon dioxide and acetylene to free carboxylic acid sites in a metal-organic framework.

The functionalisation of organic linkers in metal-organic frameworks (MOFs) to improve gas uptake is well-documented. Although the positive role of free carboxylic acid sites in MOFs for binding gas molecules has been proposed in computational studies, relatively little experimental evidence has been reported in support of this. Primarily this is because of the inherent synthetic difficulty to prepare MOF materials bearing free, accessible -COOH moieties which would normally bind to metal ions within the framework structure.

Neutron Instruments for Research in Coordination Chemistry.

Neutron diffraction and spectroscopy offer unique insight into structures and properties of solids and molecular materials. All neutron instruments located at the various neutron sources are distinct, even if their designs are based on similar principles, and thus, they are usually less familiar to the community than commercial X-ray diffractometers and optical spectrometers. Major neutron instruments in the USA, which are open to scientists around the world, and examples of their use in coordination chemistry research are presented here, along with a list of similar instruments at main neutron facilities in other countries.

Upcycling of polyethylene to gasoline through a self-supplied hydrogen strategy in a layered self-pillared zeolite.

Conversion of plastic wastes to valuable carbon resources without using noble metal catalysts or external hydrogen remains a challenging task. Here we report a layered self-pillared zeolite that enables the conversion of polyethylene to gasoline with a remarkable selectivity of 99% and yields of >80% in 4 h at 240 °C. The liquid product is primarily composed of branched alkanes (selectivity of 72%), affording a high research octane number of 88.

Small-pore hydridic frameworks store densely packed hydrogen.

Nanoporous materials have attracted great attention for gas storage, but achieving high volumetric storage capacity remains a challenge. Here, by using neutron powder diffraction, volumetric gas adsorption, inelastic neutron scattering and first-principles calculations, we investigate a magnesium borohydride framework that has small pores and a partially negatively charged non-flat interior for hydrogen and nitrogen uptake. Hydrogen and nitrogen occupy distinctly different adsorption sites in the pores, with very different limiting capacities of 2.

Exceptional capture of methane at low pressure by an iron-based metal-organic framework.

The selective capture of methane (CH) at low concentrations and its separation from N are extremely challenging owing to the weak host-guest interactions between CH molecules and any sorbent material. Here, we report the exceptional adsorption of CH at low pressure and the efficient separation of CH/N by MFM-300(Fe). MFM-300(Fe) shows a very high uptake for CH of 0.

Zr-Porphyrin Metal-Organic Framework as nanoreactor for boosting the formation of hydrogen clathrates.

We report the first experimental evidence for rapid formation of hydrogen clathrates under mild pressure and temperature conditions within the cavities of a zirconium-metalloporphyrin framework, specifically PCN-222. PCN-222 has been selected for its 1D mesoporous channels, high water-stability, and proper hydrophilic behavior. Firstly, we optimize a microwave (MW)-assisted method for the synthesis of nanosized PCN-222 particles with precise structure control (exceptional homogeneity in morphology and crystalline phase purity), taking advantage of MW in terms of rapid/homogeneous heating, time and energy savings, as well as potential scalability of the synthetic method.

Direct Conversion of Methane to Ethylene and Acetylene over an Iron-Based Metal-Organic Framework.

Conversion of methane (CH) to ethylene (CH) and/or acetylene (CH) enables routes to a wide range of products directly from natural gas. However, high reaction temperatures and pressures are often required to activate and convert CH controllably, and separating C products from unreacted CH can be challenging. Here, we report the direct conversion of CH to CH and CH driven by non-thermal plasma under ambient (25 °C and 1 atm) and flow conditions over a metal-organic framework material, MFM-300(Fe).

Ultra-fast Proton Conduction and Photocatalytic Water Splitting in a Pillared Metal-Organic Framework.

Proton-exchange membrane fuel cells enable the portable utilization of hydrogen (H) as an energy resource. Current electrolytic materials have limitation, and there is an urgent need to develop new materials showing especially high proton conductivity. Here, we report the ultra-fast proton conduction in a novel metal-organic framework, MFM-808, which adopts an unprecedented topology and a unique structure consisting of two-dimensional layers of {Zr}-clusters.

Neutron Scattering Studies of Heterogeneous Catalysis.

Understanding the structural dynamics/evolution of catalysts and the related surface chemistry is essential for establishing structure-catalysis relationships, where spectroscopic and scattering tools play a crucial role. Among many such tools, neutron scattering, though less-known, has a unique power for investigating catalytic phenomena. Since neutrons interact with the nuclei of matter, the neutron-nucleon interaction provides unique information on light elements (mainly hydrogen), neighboring elements, and isotopes, which are complementary to X-ray and photon-based techniques.

Modulation of Uptake and Reactivity of Nitrogen Dioxide in Metal-Organic Framework Materials.

We report the modulation of reactivity of nitrogen dioxide (NO ) in a charged metal-organic framework (MOF) material, MFM-305-CH in which unbound N-centres are methylated and the cationic charge counter-balanced by Cl ions in the pores. Uptake of NO into MFM-305-CH leads to reaction between NO and Cl to give nitrosyl chloride (NOCl) and NO anions. A high dynamic uptake of 6.

Dynamic crystallography reveals spontaneous anisotropy in cubic GeTe.

Cubic energy materials such as thermoelectrics or hybrid perovskite materials are often understood to be highly disordered. In GeTe and related IV-VI compounds, this is thought to provide the low thermal conductivities needed for thermoelectric applications. Since conventional crystallography cannot distinguish between static disorder and atomic motions, we develop the energy-resolved variable-shutter pair distribution function technique.

A database of synthetic inelastic neutron scattering spectra from molecules and crystals.

Inelastic neutron scattering (INS) is a powerful tool to study the vibrational dynamics in a material. The analysis and interpretation of the INS spectra, however, are often nontrivial. Unlike diffraction, for which one can quickly calculate the scattering pattern from the structure, the calculation of INS spectra from the structure involves multiple steps requiring significant experience and computational resources.

Rapid and efficient hydrogen clathrate hydrate formation in confined nanospace.

Clathrate hydrates are crystalline solids characterized by their ability to accommodate large quantities of guest molecules. Although CH and CO are the traditional guests found in natural systems, incorporating smaller molecules (e.g.

Synthesis of Nitro Compounds from Nitrogen Dioxide Captured in a Metal-Organic Framework.

Increasing levels of air pollution are driving the need for the development of new processes that take "waste-to-chemicals". Herein, we report the capture and conversion under ambient conditions of a major air pollutant, NO, using a robust metal-organic framework (MOF) material, Zr-bptc (Hbptc = 3,3',5,5'-biphenyltetracarboxylic acid), comprising {Zr(μ-O)(μ-OH)(COO)} clusters linked by 4-connected bptc ligands in an topology. At 298 K, Zr-bptc shows exceptional stability and adsorption of NO at both low (4.

Formation of a super-dense hydrogen monolayer on mesoporous silica.

Adsorption on various adsorbents of hydrogen and helium at temperatures close to their boiling points shows, in some cases, unusually high monolayer capacities. The microscopic nature of these adsorbate phases at low temperatures has, however, remained challenging to characterize. Here, using high-resolution cryo-adsorption studies together with characterization by inelastic neutron scattering vibration spectroscopy, we show that, near its boiling point (~20 K), H adsorbed on a well-ordered mesoporous silica forms a two-dimensional monolayer with a density more than twice that of bulk-solid H, rather than a bilayer.

Highly Efficient Proton Conduction in the Metal-Organic Framework Material MFM-300(Cr)·SO(HO).

The development of materials showing rapid proton conduction with a low activation energy and stable performance over a wide temperature range is an important and challenging line of research. Here, we report confinement of sulfuric acid within porous MFM-300(Cr) to give MFM-300(Cr)·SO(HO), which exhibits a record-low activation energy of 0.04 eV, resulting in stable proton conductivity between 25 and 80 °C of >10 S cm.

Direct photo-oxidation of methane to methanol over a mono-iron hydroxyl site.

Natural gas, consisting mainly of methane (CH), has a relatively low energy density at ambient conditions (~36 kJ l). Partial oxidation of CH to methanol (CHOH) lifts the energy density to ~17 MJ l and drives the production of numerous chemicals. In nature, this is achieved by methane monooxygenase with di-iron sites, which is extremely challenging to mimic in artificial systems due to the high dissociation energy of the C-H bond in CH (439 kJ mol) and facile over-oxidation of CHOH to CO and CO.

A unique Co@CoO catalyst for hydrogenolysis of biomass-derived 5-hydroxymethylfurfural to 2,5-dimethylfuran.

The development of precious-metal-free catalysts to promote the sustainable production of fuels and chemicals from biomass remains an important and challenging target. Here, we report the efficient hydrogenolysis of biomass-derived 5-hydroxymethylfurfural to 2,5-dimethylfuran over a unique core-shell structured catalyst, Co@CoO that affords the highest productivity among all catalysts, including noble-metal-based catalysts, reported to date. Surprisingly, we find that the catalytically active sites reside on the shell of CoO with oxygen vacancies rather than the metallic Co.

Structural and Dynamic Analysis of Sulphur Dioxide Adsorption in a Series of Zirconium-Based Metal-Organic Frameworks.

We report reversible high capacity adsorption of SO in robust Zr-based metal-organic framework (MOF) materials. Zr-bptc (H bptc=biphenyl-3,3',5,5'-tetracarboxylic acid) shows a high SO uptake of 6.2 mmol g at 0.