柔軟な多孔性結晶を舞台としたドナー／アクセプター配列の動的制御

二维（2D）材料如石墨、层状过渡金属二硫属化物、层状双氢氧化物和层状氮化硼的剥离已被证明产生非凡的热电、催化或分离性质。另一方面，层状多孔材料如MOFs的相关研究相对较少。虽然自上而下的方法已被用于剥离用于可剥离膜的MOF纳米片，但仍然缺乏有效的方案来选择性地获得具有所需厚度和层数的纳米片。我们合成了两个二维Cu（II）kagome MOFs，并探索了前者在极性非质子溶剂中独特的可逆膨胀现象，观察到了前所未有的双层结构中间态。在极性非质子溶剂中的2D金属有机框架（MOF）的逐步和可逆膨胀的研究过程中，我们发现了一个独特的双层中间态，这在其他MOF中没有观察到。更有趣的是，从中间和完全扩展状态开始的剥离分别导致双层和单层纳米结构的形成，为从MOFs选择性制备纳米片提供了一种新的策略。

The exfoliation of two-dimensional (2D) materials such as graphite, layered transition metal dichalcogenides, layered double hydroxides and layered boron nitrides, has been demonstrated to give rise to extraordinary thermoelectric, catalytic, or separation properties. On the other hand, related studies of layered porous materi-als such as MOFs are comparatively less explored. While the top-down approach has been employed to exfoliate MOF nanosheets for ultrathin membranes, there still lacks an effective protocol to selectively obtain nanosheets of desired thickness and number of layers. We synthesized two 2D Cu(II) kagome MOFs, and explored the unique and reversible expansion phenomenon of the former in polar aprotic solvents and observed an unprecedented intermediate state with a bilayer structure. During the investigation of the stepwise and reversible expansion of a 2D metal-organic framework (MOF) in polar aprotic solvents, we discovered a unique bilayer intermediate state that has not been observed in other MOFs. More interestingly, exfoliation initiated from the intermediate and the fully expanded states led to the formation of double and single layer nanostructures, respectively, providing a new strategy for the selective preparation of ultrathin nanosheets from MOFs.