Correlated Multimodal Approach Reveals Key Details of Nerve-Agent Decomposition by Single-Site Zr-Based Polyoxometalates

Development of technologies for protection against chemical warfare agents (CWAs) is critically important. Recently, polyoxometalates have attracted attention as potential catalysts for nerve-agent decomposition. Improvement of their effectiveness in real operating conditions requires an atomic-level understanding of CWA decomposition at the gas–solid interface. We investigated decomposition of the nerve agent Sarin and its simulant, dimethyl chlorophosphate (DMCP), by zirconium polytungstate. Using a multimodal approach, we showed that upon DMCP and Sarin exposure the dimeric tungstate undergoes monomerization, making coordinatively unsaturated Zr(IV) centers available, which activate nucleophilic hydrolysis. Further, DMCP is shown to be a good model system of reduced toxicity for studies of CWA deactivation at the gas–solid interface

A concept "bank laws" in a wide and narrow value

Досліджено сутність поняття “банківське законодавство” в широкому і вузькому значенні.Essence of concept "bank laws" in a wide and narrow value is investigated

Modeling Gas Flow Dynamics in Metal–Organic Frameworks

Modeling fluid flow dynamics in metal organic frameworks (MOFs) is a required step toward understanding mechanisms of their activity as novel catalysts, sensors, and filtration materials. We adapted a lattice Boltzmann model, previously used for studying flow dynamics in meso- and microporous media, to the nanoscale dimensions of the MOF pores. Using this model, rapid screening of permeability of a large number of MOF structures, in different crystallographic directions, is possible. The method was illustrated here on the example of an anisotropic MOF, for which we calculated permeability values in different flow directions. This method can be generalized to a large class of MOFs and used to design MOFs with the desired gas flow permeabilities

Synthesis, Structures and Photoluminescence Properties of a Series of Alkaline Earth Metal-Based Coordination Networks Synthesized Using Thiophene-Based Linkers

Three new 3-D coordination networks were synthesized using alkaline-earth metal centers, calcium, and strontium, with 2,5-thiophenedicarboxylate (TDC) as the organic linker. [Ca₂(TDC-2H)₂(DMF)₂]_<i>n</i> [<b>1</b>, space group <i>P</i>2₁/<i>n</i>, <i>a</i> = 10.0704(3) Å, <i>b</i> = 14.2521(3) Å, <i>c</i> = 17.5644(6) Å, β = 94.281(2)°] is composed of tetrameric calcium polyhedral clusters, which are connected by the organic linkers. Coordinated DMF molecules are present within the 1-D channel along the [010] direction. [Ca­(TDC-2H)]_<i>n</i> [<b>2</b>, space group <i>Pbcm</i>, <i>a</i> = 5.3331(5) Å, <i>b</i> = 6.8981(4) Å, <i>c</i> = 18.141(2) Å] consists of chains of edge-sharing calcium octahedra, connected by organic linkers, to form a dense network. [Sr­(TDC-2H)­(DMF)]_<i>n</i> [<b>3</b>, space group <i>P</i>2₁/<i>n</i>, <i>a</i> = 5.9795(3) Å, <i>b</i> = 17.058(1) Å, <i>c</i> = 11.3592(6) Å, β = 91.257(1)°] forms a structural topology almost identical to compound <b>1</b> except that the chains are built by combinations of edge- and face-sharing polyhedra. Compounds <b>1</b> and <b>3</b> were synthesized using DMF as solvent, whereas compound <b>2</b> crystallizes using ethanol. Photoluminescence studies reveal that the topologies of the networks and the presence of the coordinated solvent molecules control the luminescence properties of the compounds

Synthesis, Structures and Photoluminescence Properties of a Series of Alkaline Earth Metal-Based Coordination Networks Synthesized Using Thiophene-Based Linkers

Three new 3-D coordination networks were synthesized using alkaline-earth metal centers, calcium, and strontium, with 2,5-thiophenedicarboxylate (TDC) as the organic linker. [Ca₂(TDC-2H)₂(DMF)₂]_<i>n</i> [<b>1</b>, space group <i>P</i>2₁/<i>n</i>, <i>a</i> = 10.0704(3) Å, <i>b</i> = 14.2521(3) Å, <i>c</i> = 17.5644(6) Å, β = 94.281(2)°] is composed of tetrameric calcium polyhedral clusters, which are connected by the organic linkers. Coordinated DMF molecules are present within the 1-D channel along the [010] direction. [Ca­(TDC-2H)]_<i>n</i> [<b>2</b>, space group <i>Pbcm</i>, <i>a</i> = 5.3331(5) Å, <i>b</i> = 6.8981(4) Å, <i>c</i> = 18.141(2) Å] consists of chains of edge-sharing calcium octahedra, connected by organic linkers, to form a dense network. [Sr­(TDC-2H)­(DMF)]_<i>n</i> [<b>3</b>, space group <i>P</i>2₁/<i>n</i>, <i>a</i> = 5.9795(3) Å, <i>b</i> = 17.058(1) Å, <i>c</i> = 11.3592(6) Å, β = 91.257(1)°] forms a structural topology almost identical to compound <b>1</b> except that the chains are built by combinations of edge- and face-sharing polyhedra. Compounds <b>1</b> and <b>3</b> were synthesized using DMF as solvent, whereas compound <b>2</b> crystallizes using ethanol. Photoluminescence studies reveal that the topologies of the networks and the presence of the coordinated solvent molecules control the luminescence properties of the compounds

Structural Chemistry of Akdalaite, Al₁₀O₁₄(OH)₂, the Isostructural Aluminum Analogue of Ferrihydrite

As part of an effort to characterize clusters and intermediate phases likely to be encountered along solution reaction pathways that produce iron and aluminum oxide-hydroxides from Fe and Al precursors, the complete structure of Al10O14(OH)2 (akdalaite) was determined from a combination of single-crystal X-ray diffraction (SC-XRD) data collected at 100 K to define the Al and O positions, and solid-state nuclear magnetic resonance (NMR) and neutron powder diffraction (NPD) data collected at room temperature (~300 K) to precisely determine the nature of hydrogen in the structure. Two different synthesis routes produced different crystal morphologies. Using an aluminum oxyhydroxide floc made from mixing AlCl3 and 0.48 M NaOH, the product had uniform needle morphology, while using nanocrystalline boehmite (Vista Chemical Company Catapal D alumina) as the starting material produced hexagonal plates. Akdalaite crystallizes in the space group P63mc with lattice parameters of a = 5.6244(3) &#197; and c = 8.8417(3) &#197; (SC-XRD) and a = 5.57610(2) &#197; and c = 8.77247(6) &#197; (NPD). The crystal structure features Al13O40 Keggin clusters. The structural chemistry of akdalaite is nonideal but broadly conforms to that of ferrihydrite, the nanomineral with which it is isostructural

A Calcium Coordination Framework Having Permanent Porosity and High CO₂/N₂ Selectivity

A thermally stable, microporous calcium coordination network shows a reversible 5.75 wt % CO₂ uptake at 273 K and 1 atm pressure, with an enthalpy of interaction of ∼31 kJ/mol and a CO₂/N₂ selectivity over 45 under ideal flue gas conditions. The absence of open metal sites in the activated material suggests a different mechanism for selectivity and high interaction energy compared to those for frameworks with open metal sites

A Calcium Coordination Framework Having Permanent Porosity and High CO₂/N₂ Selectivity

A thermally stable, microporous calcium coordination network shows a reversible 5.75 wt % CO₂ uptake at 273 K and 1 atm pressure, with an enthalpy of interaction of ∼31 kJ/mol and a CO₂/N₂ selectivity over 45 under ideal flue gas conditions. The absence of open metal sites in the activated material suggests a different mechanism for selectivity and high interaction energy compared to those for frameworks with open metal sites

A Calcium Coordination Framework Having Permanent Porosity and High CO₂/N₂ Selectivity

A thermally stable, microporous calcium coordination network shows a reversible 5.75 wt % CO₂ uptake at 273 K and 1 atm pressure, with an enthalpy of interaction of ∼31 kJ/mol and a CO₂/N₂ selectivity over 45 under ideal flue gas conditions. The absence of open metal sites in the activated material suggests a different mechanism for selectivity and high interaction energy compared to those for frameworks with open metal sites