Dense Integration of Stable Aromatic Radicals within the Two-Dimensional Interlayer Space of Clay Minerals via Clay-Catalyzed Deamination of Arylammoniums
Dense Integration of Stable Aromatic Radicals within the Two-Dimensional Interlayer Space of Clay Minerals via Clay-Catalyzed Deamination of Arylammoniums
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DOI：
10.1021/acs.chemmater.0c03347
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发表时间：
2020-10-27
影响因子：
8.6
通讯作者：
Okubo, Tatsuya
中科院分区：
文献类型：
--
作者：
Kishimoto, Fuminao;Hisano, Kyohei;Okubo, Tatsuya
在这里，我们已经成功地证明了密集集成的芳基自由基阳离子内的二维层间纳米空间丰富的镁铝硅酸盐粘土矿物通过自发插入的芳基铵到粘土和随后的“粘土催化脱氨基（CCD）”的插入芳基铵的芳基自由基的形成。定量自由基测量表明，每个1-蒽基铵分子插入到皂石粘土转化为一个1-二水蒽自由基阳离子通过CCD过程。本发明的方法实现了蒽自由基阳离子在铝硅酸镁的层间空间中的极其密集的整合（类似于每1g样品190 μ mol），其密度比铝硅酸盐沸石中芳族自由基储存的报道值高近100倍。我们还可以证明芘自由基阳离子和萘自由基阳离子通过CCD与皂石层间空间内的各种取代基的整合，证实CCD过程能够实现任意芳基自由基阳离子的整合。由于层间自由基受到粘土矿物精确层状结构的保护，因此自由基表现出极高的稳定性，例如，自由基在环境条件下超过6个月不降解。更令人惊讶的是，在苛刻的条件下（高温（80摄氏度）和紫外线照射），约90%的自由基仍然存在。注意，即使具有如此高的稳定性，层状粘土矿物在溶剂体系中的原位分层也允许芳基自由基阳离子用于化学反应。可以预期，纳米腔中芳基自由基物质的这种矛盾性（高稳定性和按需反应性）将开发新的反应途径，其中自由基物质起到关键中间体的作用，例如，多相催化和自由基聚合。
Here, we have successfully demonstrated the dense integration of aryl radical cations within two-dimensional interlayer nanospace of abundant magnesium aluminosilicate clay minerals via spontaneous intercalation of the arylammoniums into the clays and a subsequent "clay-catalyzed deamination (CCD)" of the intercalated arylammoniums for aryl radical formation. Quantitative radical measurement reveals that every 1-anthrylammonium molecule intercalated into a Saponite clay converts to one 1-dihydrated anthracene radical cation via the CCD process. The current method realizes extremely dense integration of the anthracene radical cation in the interlayer space of magnesium aluminosilicate (similar to 190 mu mol per 1 g of sample), which is nearly 100 times denser than the reported values of aromatic radical storage in aluminosilicate zeolites. We can also demonstrate the integration of pyrene radical cations and naphthalene radical cations with various substituent groups within the interlayer space of Saponite via the CCD, confirming that the CCD process enables to achieve the integration of arbitrary aryl radical cations. Since the interlayer radicals are protected by the precise layered structure of clay minerals, the radicals exhibit extremely high stability, e.g., the radicals did not degrade in ambient conditions for over 6 months. More surprisingly, around 90% radicals remained under harsh conditions (high temperature (80 degrees C) and UV light irradiation). Note that even with such high stability, in situ delamination of the layered clay minerals in solvent systems allows the aryl radical cations to be used in chemical reactions. It can be expected that such the ambivalence of the aryl radical species in nanocavities (high stability and on-demand reactivity) will exploit new reaction pathways where the radical species play a role of crucial intermediates, e.g., heterogeneous catalysis and radical polymerizations.