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Two-dimensional (2D) nanomaterials are remarkably attractive platform candidates for signal transduction through fluorescence resonance energy transfer or photo-induced electron-transfer pathway. In this work, a 2D Hofmann metal organic framework (hMOF) monolayer nanosheet was developed as an axial coordination platform for DNA detection via a ligand-to-metal charge-transfer quenching mechanism. Through modulating the position of phosphonate groups of rigid ligands, a layer-structured hMOF was synthesized. The single crystals showed that the adjacent layers were linked via hydrogen bonds between diethyl 4-pyridylphosphonate and the solvent. Furthermore, the 2D hMOF monolayer nanosheets were obtained easily via a top–down method. More significantly, the quenching mechanism was identified as an axial coordination between the open Fe2+ sites of hMOF nanosheets and fluorophores with 91% quenching efficiency, constituting an excellent signal transduction strategy. The smart use of hMOF monolayer nanosheets as an axial coordination platform could lead to promising applications in signal switching or/and sensing devices.

Distinguishing glutathione (GSH) level in different subcellular locations is critical for studying its antioxidant function in the signaling system. However, traditional methods for imaging subcellular GSH were achieved in isolated organelles or fixed cells. In this work, we report a quencher‐delocalized emission strategy for in situ profiling of GSH at different subcellular locations in living cells. A nonemissive metal–organic framework (MOF) nanoprobe was designed with AIEgen as the linker and CuII as the node and quencher. The AIEgen in MOF structure was lightened up with green emission in a neutral environment due to partial CuII delocalization by competitive binding to GSH. Meanwhile, along with the protonation of AIEgen ligand under acidic environment, the AIEgen‐based MOF could be completely dissociated in the presence of GSH to yield yellow emission. The two‐channel ratiometric analysis of dual‐colored emission of AIEgen‐based MOF allows visualization of GSH in cytoplasm and lysosome in living cells, which is also able to report the drug effects on different subcellular GSH levels.

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