Hayashi Taiki, Sato Naoto, Wada Hiroaki, Shimojima Atsushi, Kuroda Kazuyuki
Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
Dalton Trans. 2021 Jun 22;50(24):8497-8505. doi: 10.1039/d1dt01122g.
Double-four ring (D4R)-type cage germanoxanes, having a fluoride anion in the cage, contain organic ammonium cations as counter cations outside the cage, and they are attractive as unique nano-building blocks of anionic porous materials. Although the variety of counter cations directly included in the cage germanoxane synthesis is limited, this study demonstrates that other tetraalkylammonium cations can be introduced by cation exchange in both discrete and cross-linked states. Tetraethylammonium (TEA) of a discrete cage germanoxane was replaced with tetrabutylammonium (TBA) in an organic solvent, which provides another starting material. TEA and TBA cations in cross-linked networks formed by hydrosilylation reactions of dimethylvinylsilylated cage germanoxanes with various oligosiloxanes as linkers were exchanged with tetramethylammonium (TMA) cations. The variation in the pore volume, which depends on the type of introduced counter cations and oligosiloxane linkers, is verified. In terms of bottom-up synthesis of nanoporous materials from cage-type germanoxanes, the selection of both the counter cation and cross-linker is important to vary the porosity.
笼中含有氟阴离子的双四环（D4R）型笼状锗氧烷，其笼外含有有机铵阳离子作为抗衡阳离子，作为阴离子多孔材料独特的纳米结构单元具有吸引力。尽管笼状锗氧烷合成中直接包含的抗衡阳离子种类有限，但本研究表明，其他四烷基铵阳离子可以通过阳离子交换以离散和交联状态引入。在有机溶剂中，离散笼状锗氧烷的四乙铵（TEA）被四丁铵（TBA）取代，这提供了另一种起始原料。通过二甲基乙烯基硅烷基化笼状锗氧烷与各种低聚硅氧烷作为连接剂的硅氢加成反应形成的交联网络中的TEA和TBA阳离子与四甲铵（TMA）阳离子进行了交换。验证了取决于引入的抗衡阳离子类型和低聚硅氧烷连接剂的孔体积变化。就从笼型锗氧烷自下而上合成纳米多孔材料而言，抗衡阳离子和交联剂的选择对于改变孔隙率很重要。
