Catalytic degradation of chemical warfare agents and their simulants by metal-organic frameworks

Solid-State Gas Adsorption Studies with Discrete Palladium(II) [Pd2 (L)4 ]4+ Cages

The need for effective CO₂ capture systems remains high, and due to their tunability, metallosupramolecular architectures are an attractive option for gas sorption. While the use of extended metal organic frameworks for gas adsorption has been extensively explored, the exploitation of discrete metallocage architectures to bind gases remains in its infancy. Herein the solid state gas adsorption properties of a series of [Pd₂ (L)₄ ]⁴⁺ lantern shaped coordination cages (L = variants of 2,6-bis(pyridin-3-ylethynyl)pyridine), which had solvent accessible internal cavities suitable for gas binding, have been investigated. The cages showed little interaction with dinitrogen gas but were able to take up CO₂ . The best performing cage reversibly sorbed 1.4 mol CO₂ per mol cage at 298 K, and 2.3 mol CO₂ per mol cage at 258 K (1 bar). The enthalpy of binding was calculated to be 25-35 kJ mol^-1 , across the number of equivalents bound, while DFT calculations on the CO₂ binding in the cage gave ΔE for the cage-CO₂ interaction of 23-28 kJ mol^-1 , across the same range. DFT modelling suggested that the binding mode is a hydrogen bond between the carbonyl oxygen of CO₂ and the internally directed hydrogen atoms of the cage.

Swellable functional hypercrosslinked polymer networks for the uptake of chemical warfare agents

Porous materials can be used as sorbents for the bulk uptake (and potential deactivation) of chemical warfare agents (CWAs).

Polyoxometalate-based gelating networks for entrapment and catalytic decontamination

A polyoxometalate-based polymer with multifunctional capabilities including rapid gelation and catalytic decontamination of toxic or odorous compounds is realized.

Metal–organic frameworks for the removal of toxic industrial chemicals and chemical warfare agents

Toxic gases can be captured or degraded by metal–organic frameworks.

Functionalized metal organic frameworks for effective capture of radioactive organic iodides

Highly efficient capture of radioactive organic iodides (ROIs) from off-gas mixtures remains a substantial challenge for nuclear waste treatment. Current materials utilized for ROI sequestration suffer from low capacity, high cost (e.g. use of noble metals), and poor recyclability. Recently, we have developed a new strategy to tackle this challenge by functionalizing MOF materials with tertiary amines to create molecular traps for the effective capture and removal of ROIs (e.g. radioactive methyl iodide) from nuclear wastes. To further enhance the uptake capacity and performance of CH₃I capture by ROI molecular traps, herein, we carry out a systematic study to investigate the effect of different amine molecules on ROI capture. The results demonstrate a record-high CH₃I saturation uptake capacity of 80% for MIL-101–Cr–DMEDA at 150 °C, which is 5.3 times that of Ag⁰@MOR (15 wt%), a leading adsorbent material for capturing ROIs during nuclear fuel reprocessing. Furthermore, the CH₃I decontamination factors (DFs) for MIL-101–Cr–DMEDA are as high as 5000 under simulated reprocessing conditions, largely exceeding that of facility regulatory requirements (DF = 3000). In addition, MIL-101–Cr–DMEDA can be recycled without loss of capacity, illustrating yet another advantage compared to known industrial adsorbents, which are typically of a “single-use” nature. Our analysis also shows that both physisorption and chemisorption of CH₃I occur at the three amine-grafted MOFs. While chemisorption takes place at the amine functionalized sites, the amount of physisorption correlates with the MOF porosity. A possible binding site of amine–CH₃I interaction has been identified via an in situ IR spectroscopic study. The results suggest that CH₃I interacts strongly and directly with the tertiary nitrogen of the amine molecules. The CH₃I uptake amount decreases as the amine chain length increases, in trend with the decreasing pore space of the corresponding framework. The strategy to build MOF-based molecular traps developed in this work not only leads to a new record-high performance for ROI capture, but also offers an effective way of systematically tuning the porosity by varying the length of functionalized amine molecules. This study also demonstrates that MOFs represent a promising new platform for selective capture and removal of radioactive nuclear waste.