Enantiopure Water-Soluble [Fe4L6] Cages: Host-Guest Chemistry and Catalytic Activity
Enantiopure Water-Soluble [Fe4L6] Cages: Host-Guest Chemistry and Catalytic Activity
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DOI：
10.1002/anie.201302136
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发表时间：
2013-07-29
影响因子：
16.6
通讯作者：
Nitschke, Jonathan R.
中科院分区：
文献类型：
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作者：
Bolliger, Jeanne L.;Belenguer, Ana M.;Nitschke, Jonathan R.
主客体化学起源于涉及通过非共价相互作用进行分子识别的生物过程，例如当底物与酶结合时。在过去的十年中，人们制备了有机胶囊 [1] 和自组装配位笼 [2]，它们能够封装各种客体，提高化学反应速率，[1c, 3] 改变涉及封装分子的反应过程，[2i, 4] 或稳定其他不稳定的物质。 [5]基于手性配体的自组装金属有机胶囊特别令人感兴趣，因为它们具有手性内部空隙，不仅可以实现对映选择性客体识别和分离，还可以为立体选择性反应提供不对称微环境。[6]已观察到小客体分子[7]被水溶性自组装四面体M4L6笼封装，该笼是通过胺、醛和FeII前体的子组分自组装制备的。在此，我们展示了如何使用带有手性甘油基的较长二氨基三联苯亚组分，如何能够对映选择性形成更大的水溶性 [Fe4L6] 胶囊。这种新的笼子封装了更广泛的客体，包括更大的分子，例如手性天然产物。我们还证明了我们的笼能够催化加速乙酰胆碱酯酶抑制剂杀虫剂敌敌畏的水解，敌敌畏与有机磷酸酯化学战剂（CWA）具有相同的关键化学特征。二氨基三联苯 4、(S, S)-4 和 (R, R)-4 由二碘氢醌 (1) 分三步制备，如方案 1 所示。 下面描述的研究是使用由对映体纯 (S, S)-4（或 (R, R)-4 或 4）、2-甲酰基吡啶和 FeIISO4 制备的 DDDD-5（或 LLLL-5 或 5）水储备溶液进行的。 6:12:4的比例（方案2）。支持信息中提供了实验细节和表征数据。深紫色胶囊 DDDD-5 的溶液给出的 FTICR 质谱与 [Fe4L6] 8+ 配方一致（支持信息中的图 S009）。通过 DOSY NMR 波谱测定，其流体动力学半径为 (15.25 Æ 0.62)，与图 1 所示模型得出的 16.1 值一致。该模型使用 ArgusLabs 的通用力场 (UFF) 进行能量最小化 [9]（图 S005）。 DDDD-5的最短FeII…FeII距离经计算约为17.1，而形成四面体边缘的双齿配体的总长度约为26.3（距离H2…H2®；方案2）。我们推断
Host–guest chemistry has its origin in biological processes involving molecular recognition through noncovalent interactions, as for example when substrates bind to enzymes. Over the last decade, organic capsules [1] and self-assembled coordination cages [2] have been prepared that are able to encapsulate a variety of guests, increase the rates of chemical reactions,[1c, 3] change the course of reactions involving encapsulated molecules,[2i, 4] or to stabilize otherwise unstable species.[5] Self-assembled metal–organic capsules based on chiral ligands are of special interest because they have a chirotopic internal void, which can not only enable enantioselective guest recognition and separation but can also provide an asymmetric microenvironment for stereoselective reactions.[6]Small guest molecules have been observed [7] to be encapsulated by a water-soluble self-assembled tetrahedral M4L6 cage prepared by subcomponent self-assembly from amine, aldehyde and FeII precursors. Herein we show how the use of a longer diamino terphenylene subcomponent, bearing chiral glyceryl groups, allows the enantioselective formation of larger water-soluble [Fe4L6] capsules. This new cage encapsulates a wider range of guests, including larger molecules, such as chiral natural products. We also demonstrate our cage s ability to accelerate catalytically the hydrolysis of the acetylcholine esterase inhibitor insecticide dichlorvos, which shares key chemical features with the class of organophosphate chemical warfare agents (CWAs). Diaminoterphenylenes 4,(S, S)-4, and (R, R)-4 were prepared in three steps from diiodohydroquinone (1) as shown in Scheme 1. The studies described below were carried out using aqueous stock solutions of DDDD-5 (or LLLL-5 or 5) prepared from enantiopure (S, S)-4 (or (R, R)-4 or 4), 2-formylpyridine, and FeIISO4 in a 6: 12: 4 ratio (Scheme2). Experimental details and characterization data are provided in the Supporting Information. A solution of the deep-purple capsule DDDD-5 gave FTICR mass spectra consistent with an [Fe4L6] 8+ formulation (Figure S009 in the Supporting Information). Its hydrodynamic radius, determined from DOSY NMR spectroscopy, was (15.25 Æ 0.62), which is consistent with the value of 16.1 derived from the model shown in in Figure 1. This model was energy-minimized using the universal force field (UFF) of ArgusLabs [9](Figure S005). The shortest FeII··· FeII distance of DDDD-5 is calculated to be approximately 17.1 while the bis-bidentate ligand forming the edge of the tetrahedron has a total length of approximately 26.3 (distance H2··· H2о; Scheme 2). We infer