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Guided by a second‐sphere interaction strategy, we fabricated a Tb(III)‐based metal—organic framework (MMCF‐4) for turn‐on sensing of methyl amine with ultra‐low detection limit and high turn‐on efficiency. MMCF‐4 features lanthanide nodes shielded in a nonacoordinate geometry along with secondary coordination spheres that are densely populated with H‐bond interacting sites. Nonradiative routes were inhibited by binding‐induced rigidification of the ligand on the second coordination sphere, resulting in luminescence amplification. Such remote interacting mechanism involved in the turn‐on sensing event was confirmed by single‐crystal X‐ray diffraction and molecular dynamic simulation studies. The design of both primary and secondary coordination spheres of Tb(III) enabled the first turn‐on sensing of organic amines in aqueous conditions. Our work suggests a promising strategy for high‐performance turn‐on sensing for Ln‐MOFs and luminous materials driven by other metal chromophores. [ABSTRACT FROM AUTHOR]

Porous materials with open metal sites have been investigated to separate various gas mixtures. However, open metal sites show the limitation in the separation of some challenging gas mixtures, such as C2H2/CO2. Herein, we propose a new type of ultra‐strong C2H2 nano‐trap based on multiple binding interactions to efficiently capture C2H2 molecules and separate C2H2/CO2 mixture. The ultra‐strong acetylene nano‐trap shows a benchmark Qst of 79.1 kJ mol−1 for C2H2, a record high pure C2H2 uptake of 2.54 mmol g−1 at 1×10−2 bar, and the highest C2H2/CO2 selectivity (53.6), making it as a new benchmark material for the capture of C2H2 and the separation of C2H2/CO2. The locations of C2H2 molecules within the MOF‐based nanotrap have been visualized by the in situ single‐crystal X‐ray diffraction studies, which also identify the multiple binding sites accountable for the strong interactions with C2H2. [ABSTRACT FROM AUTHOR]

As a major greenhouse gas, methane, which is directly vented from the coal‐mine to the atmosphere, has not yet drawn sufficient attention. To address this problem, we report a methane nano‐trap that features oppositely adjacent open metal sites and dense alkyl groups in a metal–organic framework (MOF). The alkyl MOF‐based methane nano‐trap exhibits a record‐high methane uptake and CH4/N2 selectivity at 298 K and 1 bar. The methane molecules trapped within the alkyl MOF were crystalographically identified by single‐crystal X‐ray diffraction experiments, which in combination with molecular simulation studies unveiled the methane adsorption mechanism within the MOF‐based nano‐trap. The IAST calculations and the breakthrough experiments revealed that the alkyl MOF‐based methane nano‐trap is a new benchmark for CH4/N2 separation, thereby providing a new perspective for capturing methane from coal‐mine methane to recover fuel and reduce greenhouse gas emissions. [ABSTRACT FROM AUTHOR]