Metal-Organic Framework "Molecule-Trap" Adsorbents

The development of adsorbents acting as "molecule traps" for advanced adsorption and separations on specific molecular recognition has garnered increasing attention over the past decade. Molecule trapping can be understood as strong confinement of guest molecules within well-defined local environments inside adsorbents, where adsorption is governed by geometric matching and multiple host-guest interactions rather than nonspecific van der Waals interactions alone. This site-specific trapping strategy enables precise discrimination between molecules with similar physicochemical properties under complex separation conditions. In particular, metal-organic frameworks (MOFs) provide an ideal platform for constructing molecule traps because their modular, designable, and crystalline structures enable the precise spatial organization of binding sites and confined pore environments. This Account highlights our recent advances in MOF-based molecule-trap adsorbents, from the foundational concept of the single-molecule trap to diverse trapping modes, including aromatic, localized, dynamic, and reactive trapping. These trapping modes enable selective recognition and capture/separation of hydrocarbons, greenhouse gases, and air pollutants through distinct confined interaction environments. Beyond empirical design, molecule trapping is also increasingly being guided by data-driven approaches, including large language model-assisted extraction of structure-function relationships and mechanism-based analysis. Furthermore, advances in scalable synthesis, material shaping, and continuous operation have moved MOF-based molecule-trap adsorbents closer to practical separation processes. These studies suggest that molecule trapping can serve as a useful design strategy for adsorption and separation media, providing a conceptual framework for the development of next-generation porous materials.