Defect engineered metal organic framework provides rapid detection of nerve agents

Neurological agents are highly toxic chemical warfare agents that inhibit acetylcholinesterase (AChE) in the nervous system, causing severe symptoms such as seizures and respiratory failure. Timely detection of these agents is important for protecting human health.

Current detection methods include liquid chromatography mass spectroscopy (LC-MS), ion mobility chromatography, and fluorescence techniques. Fluorescent sensing is promising due to its ease of use and local applicability, and relies primarily on the phosphorylation of nerve agents or protonation of probe molecules. However, environmental interference may limit efficacy, highlighting the need for rapid and reliable fluorescent sensing techniques for early warning of neural agent exposure.

To address these limitations, a research team led by Professor Dou Xincun of the New Jiang Institute for Technical Physics and Chemistry at the Chinese Academy of Sciences has developed a new dual-scene strategy based on chemical activity and molecular aspects for detecting phosphonyl fluoride neurogens. This work is featured in Journal Advanced Functional Materials.

Researchers used MOF-525, a zirconium-based metal organic framework (MOF), as sensing material. Characterized as a metal node with porphyrin ligands and zirconium clusters, MOF-525 exhibits high stability and resistance to acidic and basic conditions. By precisely adjusting the amount of structural modulators, the researchers synthesized a series of MOF-525 materials with various defect levels.

Optimizing modulator concentration results in material with high defect density (~60% defect rate), minimal background fluorescence, and selective sieves of fluoride nerve agents based on molecular size.

Defect engineering MOF-525 interacts with phosphonyl fluoride nerve agents, resulting in a distinct red fluorescent signal. This dual seating strategy, combining molecular size exclusion and chemical activity, allows the material to effectively distinguish between phosphonyl fluoride neuronals and structurally similar compounds.

The optimized MOF-525 demonstrated exceptional performance, including high sensitivity (0.96 nm/3.8 ppb), rapid response (<1 sec), robust resistance to acidic substances, humidity, and interference from common fluorescent materials.

This study not only elucidates the effects of defect engineering on the optical properties of MOFS, but also establishes a new paradigm for the detection and recognition of trace nerve agents.