Defect Engineering Zr-MOF-Endowed Activity-Dimension Dual-Sieving Strategy for Anti-acid Recognition of Real Phosphoryl Fluoride Nerve Agents

Defect-engineering-involved metal-organic frameworks (MOFs) have been highly valued in many fields due to the enhanced porosity and abundant active sites, but how the systematic modulation on deficiency influencing fluorescent sensing performance is still in its infancy. Here, systematic defect-engineering of MOF-525 is used to modulate the exposure of zirconium (Zr) clusters and the sieving capability of inner channels, enabling precise fluorescent sensing of phosphoryl fluoride nerve agents with specific chemical activity and molecular dimensions. Controllable defects transformed the localized emission of porphyrin into ligand-metal charge transferring (LMCT) due to the gradual loss of the ligand molecules, which is interrupted upon the coordination of nerve agents, triggering a red turn-on fluorescence. Thus, the defective MOF-525 with 60% deficiency effectively discriminates the phosphoryl fluoride nerve agents (e.g., sarin, soman) from similar substances (e.g., tabun, venomous agent X) due to synergistic sieving effect of chemical activity and molecular dimension. It exhibits highly sensitive (0.96 n m /3.8 ppb), rapid (<1 s) response toward target nerve agents and is robust to the environmental interference from the acidic, humid and common fluorescent substances. This work enhances understanding of defect-engineering MOFs and the correpsonding luminescent behavior, paving a new avenue for sensing strategy of trace real nerve agent vapor.