Paul M. Forster

Zeolite-like Metal−Organic Frameworks (ZMOFs) as Hydrogen Storage Platform: Lithium and Magnesium Ion-Exchange and H2-(rho-ZMOF) Interaction Studies

Zeolite-like metal-organic frameworks (ZMOFs) are anionic, have readily exchangeable extra-framework cations, and can be constructed with a variety of organic linkers. ZMOFs therefore can be regarded as an excellent platform for systematic studies of the effect(s) of various structural factors on H(2) binding/interaction with porous metal-organic materials. We find that the enhanced binding of molecular hydrogen in ion-exchanged ZMOFs with an anionic framework is largely governed by the presence of the electrostatic field in the cavity, which is reflected by isosteric heats of adsorption in these compounds which are greater by as much as 50% relative to those in neutral MOFs. Direct contact of the sorbed hydrogen with the exchangeable cations is shown not to be possible in the explored systems thus far, as they retain their form as aqua complexes.

Enhancing H2 Uptake by “Close-Packing” Alignment of Open Copper Sites in Metal–Organic Frameworks†

Inspired by close-packing of spheres, to strengthen the framework-H{sub 2} interaction in MOFs (metal-organic frameworks), a strategy is devised to increase the number of nearest neighboring open metal sites ofe ach H{sub 2}-hosting cage, and to align the open metal sites toward the H{sub 2} molecules. Two MOF polymorphs were made, one exhibiting a record high hydrogen uptake of 3.0 wt% at 1 bar and 77 k.

Nickel(II) Phosphate VSB‐5: A Magnetic Nanoporous Hydrogenation Catalyst with 24‐Ring Tunnels

Nanoporosity, good thermal stability, antiferromagnetic ordering, and hydrogenation with basic catalytic character are four important properties of the large-pore (24MR), zeolitic nickel(II) phosphate, VSB-5 (Ni20 [(OH)12 (H2 O)6 ][(HPO4 )8 (PO4 )4 ]⋅12 H2 O), which has been prepared under alkaline hydrothermal conditions. The structure of VSB-5 is depicted: NiO6 octahedra: green; PO4 tetrahedra: red.

The role of temperature in the synthesis of hybrid inorganic–organic materials: the example of cobalt succinates

Five different cobalt succinate materials synthesized from an identical starting mixture using temperature as the only independent variable show increasing condensation and density at higher synthesis temperatures.

Hybrid Inorganic–Organic Solids: An Emerging Class of Nanoporous Catalysts

Nanoporous hybrid materials, both metal-organic coordination polymers and hybrid metal oxides, have recently developed into an important new class of solid-state compounds. Potential applications in the field of heterogeneous catalysis include acid, shape-selective, chiral, ship-in-a-bottle, and shape-recognition-driven reactions. Here, we summarize the synthesis, structural features, chemical functionality, and catalytic properties of this unique family of materials.

Nanoporous metal formates for krypton/xenon separation

Metal(II) formates (Co and Ni) show a significantly larger heat of adsorption for xenon than krypton across all loadings due to size selectivity in the primary adsorption site.

Self-assembly of halogen substituted phenazines

This paper reports the effect of halogen substituents on the morphology of self-assembling phenazines. Asymmetrically substituted phenazines with decyloxy substituents and halogens (F, Cl, Br, and I) were prepared. Thermal properties were characterized with differential scanning calorimetry (DSC), while polarized optical microscopy (POM) and UV-vis spectroscopy on the cast films of the compounds revealed their assembling ability. A more detailed investigation on the self-assembly was conducted with a phase transfer method. A dramatic morphology difference was observed according to the type of halogen substituents. From F to Cl to Br to I, structures with more one-dimensional (1D) character were produced as confirmed by scanning electron microscopy (SEM). Single crystal X-ray crystallography on Cl substituted phenazine demonstrated hydrogen bonding as the major driving force responsible for the assembly in the longest crystal dimension, while π–π and van der Waals interactions contribute to the growth in the width and thickness directions, respectively. The Br or I substituted phenazines produced assembled structures with more 1D character than either F or Cl substituted phenazines. In addition to the assembly using a phase transfer method, we also present gelation properties for these compounds using select organic solvents.

Technetium Dichloride: A New Binary Halide Containing Metal–Metal Multiple Bonds

Technetium dichloride has been discovered. It was synthesized from the elements and characterized by several physical techniques, including single crystal X-ray diffraction. In the solid state, technetium dichloride exhibits a new structure type consisting of infinite chains of face sharing [Tc(2)Cl(8)] rectangular prisms that are packed in a commensurate supercell. The metal-metal separation in the prisms is 2.127(2) Å, a distance consistent with the presence of a Tc≡Tc triple bond that is also supported by electronic structure calculations.

Synthesis and structure of technetium trichloride.

Technetium trichloride has been synthesized by reaction of Tc(2)(O(2)CCH(3))(4)Cl(2) with HCl(g) at 300 °C. The mechanism of formation mimics the one described earlier in the literature for rhenium. Tc(2)(O(2)CCH(3))(2)Cl(4) [P1̅; a = 6.0303(12) Å, b = 6.5098(13) Å, c = 8.3072(16) Å, α = 112.082(2)°, β = 96.667(3)°, γ = 108.792(3)°; Tc-Tc = 2.150(1) Å] is formed as an intermediate in the reaction at 100 °C. Technetium trichloride is formed above 250 °C and is isostructural with its rhenium homologue. The structure consists of Tc(3)Cl(9) clusters [R3̅m; a = b = 10.1035(19) Å, c = 20.120(8) Å], and the Tc-Tc separation is 2.444(1) Å. Calculations on TcX(3) (X = Cl, Br) have confirmed the stability of TcCl(3) and suggest the existence of a polymorph of TcBr(3) with the ReBr(3) structure.

Pair distribution function analysis of pressure treated zeolite Na-A

Pair distribution function studies using X-ray scattering data from zeolite Na-A samples treated at pressure up to 8 GPa indicate a pressure-induced amorphisation mechanism involving loss of crystallographic order of the aluminosilicate framework but retention of the local sodium to oxygen bonding.