The highly sensitive and specific detection of nerve agents is crucial for safeguarding national security and ensuring human health, showing prominent academic significance and application prospect. In recent years, Xinjiang Key Laboratory of Trace Chemical Substances Sensing, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, has made significant progress in the design of nerve agent sensing materials, modulating fluorescent probe structures, and elucidating sensing mechanisms (Angew. Chem. Int. Ed. 2024, 63, 202400453, Adv. Funct. Mater. 2025, 2425082, ACS Appl. Mater. Interfaces 2025, 17, 25722, Cell Rep. Phys. Sci. 2025, 6, 102721).

Metal-Organic Framework (MOF), which has the characteristics of diverse topological structures, large specific surface area, effective size-sieving properties, abundant recognition sites, tunable ligand structures, and the relative ease of constructing multiple luminescent centers, has gradually emerged as novel materials in the field of fluorescent gas sensing. However, research on the design of MOF-based materials for trace-level nerve agent detection remains relatively limited.

To achieve high-performance detection of sarin/DCP, a new recognition strategy based on rotation-restricted emission mechanism was explored for the first time. A carbazole-based lanthanide metal-organic framework (Eu-CTTB-MOF) with red fluorescence emission was constructed using carbazole groups as the primary recognition sites for sarin, 4,4′,4″,4‴-(9H-carbazole-1,3,6,8-tetrayl)tetrabenzoic acid (H₄CTTB) as the ligand, and the lanthanide metal europium (Eu) as the metal node. An unprecedented specific recognition of nerve-agent sarin mimic diethyl chlorophosphate (DCP) in the presence of HCl interferent and a low limit of detection (LOD, 20.97 nM) were achieved. This excellent detection performance is driven by the dual hydrogen bonding and hydrophobic interaction between the CTTB organic ligand and DCP, which would cause a dramatic change in the molecular configuration of the CTTB ligand. Density functional theory (DFT) calculations further verify the recognition of DCP by Eu-CTTB-MOF could suppress the rotations of the aromatic rings in CTTB ligand, significantly reducing the nonradiative decay pathways and subsequently enhancing the fluorescent intensity of the CTTB ligand. Especially, the Eu-CTTB-MOF enables the immediate response to DCP vapor and excellent specificity towards DCP even in the presence of 18 types of interferents, including HCl vapor, structural analogs, and volatile organic solvent, and a gas detector with accurate detection of DCP in simulated scenarios, positioning the designed MOF as a promising sensing material for practical scenarios.

This work, titled “Exactly Restricting the Phenyl Ring Rotation in Metal-Organic Framework for Ultra-Sensitive and Specific Ratiometric Fluorescent Sensing of Sarin”, was published in Aggregate and selected as the inside front cover. The work is financially supported by the National Key Research and Development Program of China, National Natural Science Foundation of China, Tianshan Innovation Team Plan, and the Youth Innovation Promotion Association, CAS.