Pore‐Space‐Partition Enabled Through‐Space‐Charge‐Transfer in Metal–Organic Frameworks for Enhanced Sarin Simulant Recognition

Abstract While through‐space charge transfer (TSCT) is proven as an effective mechanism for achieving dynamic and environment‐sensitive luminescence in rigid U‐shaped small‐molecule systems, the rational design of TSCT‐based materials keeps challenging. Herein, the pore‐space‐partition (PSP) strategy is proposed to precisely arrange donor–acceptor units within magnesium‐based MOFs (SNNU‐265 to SNNU‐267), constructed by co‐assembling tris(4‐(pyridin‐4‐yl)phenyl)amine (TPPA) with amino‐functionalized biphenyl dicarboxylates. These dual‐ligand MOFs exhibit confined donor–acceptor alignment in narrow channels, facilitating TSCT‐based fluorescence and sensing. As expected, upon exposure to the sarin simulant diethyl chlorophosphate (DCP), protonation of amino groups in SNNU‐266 and SNNU‐267 forms localized ─NH ₃ ⁺ acceptor sites, triggering TSCT from the electron‐rich TPPA donors to the carboxylate‐based acceptors. This electron redistribution induces pronounced red‐shifted fluorescence quenching in both solution and vapor phases. Specially, SNNU‐266 and SNNU‐267 exhibit ultralow detection limits (0.017–0.025 ppm in solution; 0.04–0.08 ppm in vapor), rapid response (<10 s), high selectivity, and full recyclability. The ¹ H NMR titration, in situ FT‐IR spectroscopy, and DFT calculations confirm that this TSCT mechanism is protonation‐induced and confined within the rigid MOF lattice. Overall, this work demonstrates a simple and universal strategy for rational control of through‐space charge transfer in MOFs, which enables a super‐real‐time detection ability for nerve agent simulants.