Counting the Acid Sites in a Commercial ZSM-5 Zeolite Catalyst.

This work investigates the acid sites in a commercial ZSM-5 zeolite catalyst by a combination of spectroscopic and physical methods. The Brønsted acid sites in such catalysts are associated with the aluminum substituted into the zeolite lattice, which may not be identical to the total aluminum content of the zeolite. Inelastic neutron scattering spectroscopy (INS) directly quantifies the concentrations of Brønsted acid protons, silanol groups, and hydroxyl groups associated with extra-framework aluminum species.

Proton and Oxide Ion Conductivity in Palmierite Oxides.

Solid proton and oxide ion conductors have key applications in several hydrogen-based and energy-related technologies. Here, we report on the discovery of significant proton and oxide ion conductivity in palmierite oxides AVO (A = Sr, Ba), which crystallize with a framework of isolated tetrahedral VO units. We show that these systems present prevalent ionic conduction, with a large protonic component under humidified air ( ∼ 0.

High oxide ion and proton conductivity in a disordered hexagonal perovskite.

Oxide ion and proton conductors, which exhibit high conductivity at intermediate temperature, are necessary to improve the performance of ceramic fuel cells. The crystal structure plays a pivotal role in defining the ionic conduction properties, and the discovery of new materials is a challenging research focus. Here, we show that the undoped hexagonal perovskite BaNbMoO supports pure ionic conduction with high proton and oxide ion conductivity at 510 °C (the bulk conductivity is 4.

Hexagonal perovskite derivatives: a new direction in the design of oxide ion conducting materials.

Various structural families have been reported to support oxide ion conductivity; among these, perovskite conductors have received particular attention. The perovskite structure is generally composed of a framework of corner-sharing octahedral units. When the octahedral units share their faces, hexagonal perovskites are formed.

Relationship between the Crystal Structure and Electrical Properties of Oxide Ion Conducting BaWNbO.

The oxide ionic conductor BaWNbO has been synthesized as part of an investigation into the new class of BaM'M''O (M' = W, Mo; M'' = Nb) oxide-ion conducting hexagonal perovskite derivatives. The substitution of W for Nb in BaWNbO leads to an increase in the oxygen content, which enhances the low-temperature ionic conductivity. However, at 400 °C, the ionic conductivity of BaWNbO is still significantly lower than the molybdenum compound BaMoNbO.

Electrical and Structural Characterization of BaMoNbO: The Relationship between Mixed Coordination, Polyhedral Distortion and the Ionic Conductivity of BaMoNbO.

The electrical and structural properties of the series BaMoNbO (x = 0.0, 0.1, 0.

The Crystal Structure of BaNbO Revisited: A Neutron Diffraction and Solid-State NMR Study.

The structure of BaNbO has been investigated using high resolution neutron powder diffraction. Our results show that, while the structure has some features in common with the 9R perovskite and palmierite structures, it is a new and distinct structure. It is shown to follow a (chh)(hhc)(chh) sequence with BaO packing layers and is a cation- and anion-deficient 9H perovskite polytype.

Oxide Ion Conductivity in the Hexagonal Perovskite Derivative BaMoNbO.

Oxide ion conductors are important materials with a range of technological applications and are currently used as electrolytes for solid oxide fuel cells and solid oxide electrolyzer cells. Here we report the crystal structure and electrical properties of the hexagonal perovskite derivative BaMoNbO. BaMoNbO crystallizes in a hybrid of the 9R hexagonal perovskite and palmierite structures.

Furthering the understanding of silicate-substitution in α-tricalcium phosphate: an X-ray diffraction, X-ray fluorescence and solid-state nuclear magnetic resonance study.

High-purity (SupT) and reagent-grade (ST), stoichiometric and silicate-containing α-tricalcium phosphate (α-TCP: ST0/SupT0 and Si-TCP x=0.10: ST10/SupT10) were prepared by solid-state reaction based on the substitution mechanism Ca3(PO4)(2-x)(SiO4)x. Samples were determined to be phase pure by X-ray diffraction (XRD), and Rietveld analysis performed on the XRD data confirmed inclusion of Si in the α-TCP structure as determined by increases in unit cell parameters; particularly marked increases in the b-axis and β-angle were observed.

The role of the chemical composition of monetite on the synthesis and properties of α-tricalcium phosphate.

There has been a resurgence of interest in alpha-tricalcium phosphate (α-TCP), with use in cements, polymer composites and in bi- and tri-phasic calcium phosphate bone grafts. The simplest and most established method for preparing α-TCP is the solid state reaction of monetite (CaHPO4) and calcium carbonate at high temperatures, followed by quenching. In this study, the effect of the chemical composition of reagents used in the synthesis of α-TCP on the local structure of the final product is reported and findings previously reported pertaining to the phase composition and stability are also corroborated.

Colossal magnetoresistance in Mn2+ oxypnictides NdMnAsO(1-x)F(x).

Colossal magnetoresistance is a rare phenomenon in which the electronic resistivity of a material can be decreased by orders of magnitude upon application of a magnetic field. Such an effect could be the basis of the next generation of memory devices. Here we report CMR in the antiferromagnetic oxypnictide NdMnAsO(1-x)F(x) as a result of competition between an antiferromagnetic insulating phase and a paramagnetic semiconductor upon application of a magnetic field.

Giant magnetoresistance in oxypnictides (La,Nd)OMnAs.

A sizeable negative magnetoresistance (MR) has been observed for oxypnictides LnOMnAs (Ln = La,Nd). MR up to -24% is observed at 200 K for LaOMnAs which is unprecedented for divalent Mn(2+). Both materials are weak ferromagnets with transition temperatures above room temperature.

Methyl 1-{4-[(S)-2-(meth-oxy-carbon-yl)pyrrolidin-1-yl]-3,6-dioxocyclo-hexa-1,4-dien-1-yl}pyrrolidine-2-carboxyl-ate.

The complete mol-ecule of the title diproline ester quinone, C(18)H(22)N(2)O(6), is generated by a crystallographic twofold axis, which passes through the centre of the benzene ring. Both -CO(2)Me groups are orientated to the same side of the benzene ring, with the carbonyl groups pointing roughly towards each other. The conformation of the proline residue is an envelope.

μ-Acetato-bis-(μ-2-{[(3-chloro-2-hydroxy-prop-yl)(2-pyridylmeth-yl)amino]meth-yl}phenolato)dinickel(II) chloride.

The title salt, [Ni(2)(C(16)H(18)ClN(2)O(2))(2)(CH(3)COO)]Cl, features a dinuclear cation in which the Ni atoms are triply bridged by two phenolate O ligands and a bidentate acetate ligand with all of the bridging distances essentially symmetric. Each Ni atom is also coordinated by the amine N, pyridine N and hydr-oxy O atoms of the 2-{[(3-chloro-2-hydroxy-prop-yl)(2-pyridylmeth-yl)amino]meth-yl}phenolate ligand which is, therefore, penta-dentate. The resultant N(3)O(3) donor sets define octa-hedral coordination geometries.

A comparison of cortical and trabecular bone from C57 Black 6 mice using Raman spectroscopy.

Cortical and trabecular bone are both produced and maintained by the same cell types. At the microscopic scale they have a similar lamellar structure but at a macroscopic scale they are very different. Raman microscopy has been used to investigate compositional differences in the two bone types using bone from standard laboratory mice in physiological conditions.

1-[2-(Carboxy-meth-oxy)phen-yl]-N-(4-chloro-phen-yl)methanimine oxide.

In the title resonance conformer, C(15)H(12)ClNO(4), the central C-N bond [1.297 (2) Å] has considerable double-bond character and the N-O bond [1.3215 (18) Å] indicates formal negative charge on the oxygen atom.

Bis[1-(isopropyl-ideneamino)guanidinium] bis-(3-nitro-benzoate) monohydrate.

The asymmetric unit of the title salt hydrate, 2C(4)H(11)N(4) (+)·2C(7)H(4)NO(4) (-)·H(2)O, comprises two independent 1-(isopropyl-ideneamino)guanidinium cations, two independent 3-nitro-benzoate anions and a water mol-ecule of crystallization. There are minimal geometric differences between the two planar [maximum deviations 0.061 (2) and 0.

Cyclic and acyclic products from the reactions between methyl 3-oxobutanoate and arylhydrazines.

The molecules of methyl 3-(2-nitrophenylhydrazono)butanoate, C(11)H(13)N(3)O(4), (I), and methyl 3-(2,4-dinitrophenylhydrazono)butanoate, C(11)H(12)N(4)O(6), (II), both prepared from methyl 3-oxobutanoate and the corresponding nitrophenylhydrazine, exhibit polarized molecular electronic structures; in each of (I) and (II), the molecules are linked into chains by a single C-H...

Isomeric N-(iodophenyl)nitrobenzamides form different three-dimensional framework structures.

The isomeric N-(iodophenyl)nitrobenzamides, C(13)H(9)IN(2)O(3), all form different three-dimensional framework structures. Molecules of N-(2-iodophenyl)-3-nitrobenzamide (II) are linked by a combination of N-H..

Isomers and polymorphs of (E,E)-1,4-bis(nitrophenyl)-2,3-diaza-1,3-butadienes.

The structures of five of the possible six isomers of (E,E)-1,4-bis(nitrophenyl)-2,3-diaza-1,3-butadiene are reported, including two polymorphs of one of the isomers. (E,E)-1,4-Bis(2-nitrophenyl)-2,3-diaza-1,3-butadiene, C(14)H(10)N(4)O(4) (I), crystallizes in two polymorphic forms (Ia) and (Ib) in which the molecules lie across centres of inversion in space groups P2(1)/n and P2(1)/c, respectively: the molecules in (Ia) and (Ib) are linked into chains by aromatic pi..

N-(2-Hydroxy-3-iodo-5-nitrobenzylidene)-3-nitroaniline: conformational isomers linked into complex sheets by five C-H...O hydrogen bonds and a two-centre iodo-nitro interaction.

The title compound, C(13)H(8)IN(3)O(5), crystallizes with Z' = 2 in the space group P2(1)/n. The two independent molecules, which are both almost planar, are conformational isomers. The molecules are linked into complex sheets by a combination of five independent C-H.

4-Iodo-N,N-bis(2-nitrophenylsulfonyl)aniline: a three-dimensional framework structure built from six independent C-H...O hydrogen bonds.

In the title compound [systematic name: 4-iodophenylimino bis(2-nitrobenzenesulfinate)], C(18)H(12)IN(3)O(8)S(2), where the molecules do not exhibit even approximate local symmetry, the molecules are linked into a complex three-dimensional structure by six independent C-H...

Formation of ladders from R(4)4(8) and R(6)6(12) rings in 8-hydroxyquinolinium chloride monohydrate: comparisons with the supramolecular arrangements in related salts.

Molecules of the title compound, C9H8NO+.Cl-.H2O, are linked into two rings by strong hydrogen bonding via the free water molecules and the Cl- anions.

3-(3-Nitrophenylaminocarbonyl)propionic acid: hydrogen-bonded sheets of alternating R(2)(2)(8) and R(6)(6)(36) rings.

Molecules of the title compound, C10H10N2O5, are linked by a combination of O-H...