Benign Synthesis and Modification of a Zn–Azolate Metal–Organic Framework for Enhanced Ammonia Uptake and Catalytic Hydrolysis of an Organophosphorus Chemical

Cao, Ran; Mian, Mohammad Rasel; Liu, Xinyao; Chen, Zhijie; Wasson, Megan C.; Wang, Xingjie; Idrees, Karam B.; Ma, Kaikai; Sun, Qijun; Li, Jian‐Rong; İslamoğlu, Timur; Farha, Omar K.

doi:10.1021/acsmaterialslett.1c00420

Cited by 17 publications

(11 citation statements)

References 42 publications

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“…In aqueous solution, the organophosphorus moiety present in many warfare agents coordinates to the Zr node while homogeneous, outer-sphere bases hydrolyze the bound agent. The Zn-based MOF MFU-4l ,, and Ti-based MOF MUV-100 have also shown promise as catalysts for nerve agent degradation, with the Zn and Ti nodes demonstrating a similar role to that of Zr, the Lewis acidic active site in nerve-agent hydrolysis.…”

Section: Introductionmentioning

confidence: 99%

Aqueous-Phase Destruction of Nerve-Agent Simulants at Copper Single Atoms in UiO-66

et al. 2022

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Metal−organic frameworks (MOFs) have shown great success in aqueous-phase hydrolysis of nerve agents, with some even showing promise in the gas phase. However, both aqueous-phase reactivity and gas-phase reactivity are hindered because of the binding of the hydrolyzed products to the MOF nodes in a stable, bridging configuration, which limits turnover. Single transition-metal atoms in MOFs have been a growing field of interest for catalytic applications, and single atoms have been proposed to prevent the unwanted bridged conformation and increase catalytic turnover. To date, there has been little experimental evidence to support the hypothesis. Herein, we report two copper single atom-modified UiO-66 MOFs for nerveagent simulant degradation. Despite the capping of highly active Zr 4+ nodes with fewer Lewis acidic Cu n+ atoms, the reactivity of both CuMOFs approaches that of native UiO-66 under aqueous conditions. Computational studies reveal that the Cu coordination environment impairs product inhibition with respect to the native MOF.

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Section: Introductionmentioning

confidence: 99%

Aqueous-Phase Destruction of Nerve-Agent Simulants at Copper Single Atoms in UiO-66

et al. 2022

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“…First explored in 2014 by Katz et al, UiO-66 showed promising activity for the hydrolysis and methanolysis of organophosphate (OP) compounds used as simulants for more toxic CWAs under humid or aqueous conditions . Since then, other Zr-based MOFs such as UiO-67, MOF-808, NU-1000, and others have been investigated for OP hydrolysis with similar mechanisms proposed for each structure. − Previous studies have suggested increases in reactivity due to increased open metal sites (MOF-808) or increased diffusion (NU-1000), but benchmarking materials against UiO-66 is difficult due to different particle sizes and defect levels, which may play a significant role in reactivity.…”

Section: Introductionmentioning

confidence: 99%

Defect Level and Particle Size Effects on the Hydrolysis of a Chemical Warfare Agent Simulant by UiO-66

et al. 2021

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Defect engineering in metal−organic frameworks (MOFs) has recently become an area of significant research due to the possibility of enhancing material properties such as internal surface area and catalytic activity while maintaining stable 3D structures. Through a modulator screening study, the model Zr 4+ MOF, UiO-66, has been synthesized with control of particle sizes (100−1900 nm) and defect levels (2−24%). By relating these properties, two series were identified where one property remained constant, allowing for independent analysis of the defect level or particle size, which frequently change coincident with the modulator choice. The series were used to compare UiO-66 reactivity for the hydrolysis of a chemical warfare agent simulant, dimethyl 4-nitrophenylphosphate (DMNP). The rate of DMNP hydrolysis displayed high dependence on the external surface area, supporting a reaction dominated by surface interactions. Moderate to high concentrations of defects (14−24%) allow for the accessibility of some interior MOF nodes but do not substantially promote diffusion into the framework. Individual control of defect levels and particle sizes through modulator selection may provide useful materials for small molecular catalysis and provide a roadmap for similar engineering of other zirconium frameworks.

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“…MOFs have been established as excellent platform materials in a variety of applications, including catalysis, , gas storage and separations, − and chemical sensing, − due to their high surface areas and ease of structural tunability. Importantly, excellent control over the pore environment has enabled selective uptake with high capacities for MOFs toward targeted analytes, including NH 3 − and SO 2 . − Among these materials, zirconium-based MOFs (Zr-MOFs) show great promise as they exhibit excellent chemical and thermal stability and a significant degree of topological diversity . For example, Zr-MOFs feature [Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 ] 12+ nodes that contain both Lewis acidic open metal sites and Brønsted acidic bridging and terminal hydroxo ligands that can engage in various modes of reactivity (Figure ), and varying the identity and geometry of the carboxylate linker offers access to many different network topologies.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Influence of Hexanuclear Clusters in Isostructural Metal–Organic Frameworks on Toxic Gas Adsorption

Kirlikovali

Chen

Wang

et al. 2022

ACS Appl. Mater. Interfaces

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The efficient capture of toxic gases, such as ammonia (NH3) and sulfur dioxide (SO2), can protect the general population and mitigate widespread air pollution. Metal–organic frameworks (MOFs) comprise a tunable class of adsorbents with high surface areas that can meet this challenge by selectively capturing these gases at low concentrations. In this work, we explored how modifying the metal ions in the node of an isostructural MOF series from a transition metal to a lanthanide or actinide influences the electronic environment of the node-based active site. Next, we investigated the adsorption properties of each MOF toward the relatively basic NH3 and relatively acidic SO2 gases. Within the NU-907 family of MOFs, we found that Zr6-NU-907 exhibits the best uptake toward NH3 at low pressures, while Th6-NU-907 demonstrates the best low-pressure performance for SO2 adsorption. Tracking the infrared (IR) stretching frequency of the node-based μ3-OH groups provides insights into the electronegativity of the metal ion and suggests that the most electronegative metal ion (Zr) affords the node with the best NH3 uptake at low pressures. In contrast, the Th6 node contains additional coordinated water groups relative to the other M6 nodes, which appears to yield the MOF with the greatest affinity for SO2 uptake that occurs predominately through reversible physisorption interactions. Finally, in situ NH3 IR spectroscopic studies indicate that both NH4 + and Lewis-bound NH3 species form during adsorption. Combined, these results suggest that tuning the electronic properties and structure of the node-based active site in an MOF presents a viable strategy to change the affinity of an MOF toward toxic gases.

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Benign Synthesis and Modification of a Zn–Azolate Metal–Organic Framework for Enhanced Ammonia Uptake and Catalytic Hydrolysis of an Organophosphorus Chemical

Cited by 17 publications

References 42 publications

Aqueous-Phase Destruction of Nerve-Agent Simulants at Copper Single Atoms in UiO-66

Aqueous-Phase Destruction of Nerve-Agent Simulants at Copper Single Atoms in UiO-66

Defect Level and Particle Size Effects on the Hydrolysis of a Chemical Warfare Agent Simulant by UiO-66

Investigating the Influence of Hexanuclear Clusters in Isostructural Metal–Organic Frameworks on Toxic Gas Adsorption

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