Al Danaf Nader, Schrimpf Waldemar, Hirschle Patrick, Lamb Don C, Ji Zhe, Wuttke Stefan
Department of Chemistry and Center for NanoScience, University of Munich, Butenandtstraße 5-13, 81377 Munich, Germany.
Department of Chemistry, University of California-Berkeley, Berkeley, California 94720, United States.
J Am Chem Soc. 2021 Jul 21;143(28):10541-10546. doi: 10.1021/jacs.1c04804. Epub 2021 Jul 6.
In metal-organic frameworks (MOFs), organic linkers are subject to postsynthetic exchange (PSE) when new linkers reach sites of PSE by diffusion. Here, we show that during PSE, a bulky organic linker is able to penetrate narrow-window MOF crystals. The bulky linker migrates by continuously replacing the linkers gating the otherwise impassable windows and serially occupying an array of backbone sites, a mechanism we term . A necessary consequence of this process is the accumulation of missing-linker defects along the diffusion trajectories. Using fluorescence intensity and lifetime imaging microscopy, we found a gradient of missing-linker defects from the crystal surface to the interior, consistent with the spatial progression of PSE. Our success in incorporating bulky functional groups via PSE extends the scope of MOFs that can be used to host sizable, sophisticated guest species, including large catalysts or biomolecules, which were previously deemed only incorporable into MOFs of very large windows.
在金属有机框架（MOF）中，当新的连接体通过扩散到达后合成交换（PSE）位点时，有机连接体会发生后合成交换。在此，我们表明在PSE过程中，一个体积较大的有机连接体能够穿透窄窗口MOF晶体。该体积较大的连接体通过不断取代控制原本无法通过的窗口的连接体并依次占据一系列骨架位点来迁移，我们将这种机制称为 。这一过程的必然结果是沿着扩散轨迹积累缺失连接体缺陷。使用荧光强度和寿命成像显微镜，我们发现从晶体表面到内部存在缺失连接体缺陷的梯度，这与PSE的空间进展一致。我们通过PSE成功引入体积较大的官能团，扩展了可用于容纳大型、复杂客体物种的MOF的范围，这些客体物种包括大型催化剂或生物分子，而这些物种以前被认为只能纳入具有非常大窗口的MOF中。
