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、层状过渡金属二卤化物、层状双氢氧化物和层状氮化硼的剥离，已被证明具有非凡的热电、催化或分离性能。另一方面，MOF等层状多孔材料的相关研究相对较少。虽然自顶向下的方法已经被用来剥离用于超薄薄膜的MOF纳米片，但仍然缺乏一种有效的协议来选择性地获得所需的厚度和层数的纳米片。我们合成了两个二维铜(II)Kagome MOF，探索了前者在极性非质子溶剂中独特的可逆膨胀现象，观察到了一个前所未有的双层结构的中间态。在研究二维金属-有机骨架(MOF)在极性非质子溶剂中的逐步可逆展开过程中，我们发现了一种独特的双层中间态，这是其他MOF中没有观察到的。更有趣的是，从中间态和完全膨胀态开始的剥离分别导致了双层和单层纳米结构的形成，为从MOF中选择性地制备超薄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.