Recent progress of MOF-based photoluminescent platforms: a comprehensive overview of their applications in biosensing and underlying mechanisms.

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Metal−organic frameworks (MOFs) with open metal sites (OMSs) have been shown to preferentially adsorb unsaturated hydrocarbons such as C 2 H 4 due to the formation of π-complexation. However, the adsorption capacity and selectivity might well be dampened under humid conditions because OMSs could be easily poisoned in the presence of water vapor. C 2 H 6selective adsorbents with less hydrophilic environments, on the other hand, not only could effectively minimize the impact of humidity on separation capacity but also could directly produce high-purity C 2 H 4 from C 2 H 6 /C 2 H 4 mixtures. Here, we report a C 2 H 6 -selective MOF (JNU-2) underlying a rare xae topology. Its cage-like cavities are interconnected through apertures with a limiting diameter of ca. 3.7 Å, which is in the domain of kinetic diameters of C 2 H 4 and C 2 H 6 molecules. Molecular modeling studies suggest the four oxygen atoms on aperture are poised to preferentially interact with C 2 H 6 through multiple C−H•••O hydrogen bonding, rendering JNU-2 an enhanced C 2 H 6 selectivity. Indeed, experimental results reveal that JNU-2 not only takes up a great amount of C 2 H 6 comparable to other top-performing C 2 H 6 -selective MOFs but also displays excellent separation capacity even under humid conditions; moreover, it can be easily regenerated at room temperature owing to its moderate adsorption enthalpy. This work successfully demonstrated a strategy of balancing adsorption capacity and selectivity for C 2 H 6 by designing MOF materials with cavities interconnected through tailored apertures. The apertures function as screening sites for C 2 H 6 selectivity, while the internal cavities provide space for large adsorption.

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Porous materials that can undergo pore‐structure adjustment to better accommodate specific molecules are ideal for separation and purification. Here, we report a stable microporous metal‐organic framework, JNU‐1, featuring one‐dimensional diamond‐shaped channels with a high density of open metal sites arranged on the surface for the cooperative binding of acetylene. Together with its framework flexibility and appropriate pore geometry, JNU‐1 exhibits an induced‐fit behavior for acetylene. The specific binding sites and continuous framework adaptation upon increased acetylene pressure are validated by molecular modeling and in situ X‐ray diffraction study. This unique induced‐fit behavior endows JNU‐1 with an unprecedented increase in the acetylene binding affinity (adsorption enthalpy: up to 47.6 kJ mol−1 at ca. 2.0 mmol g−1 loading).