Synthesis and crystal structure of double-three ring (D3R)-type cage siloxanes modified with dimethylsilanol groups
Synthesis and crystal structure of double-three ring (D3R)-type cage siloxanes modified with dimethylsilanol groups
复制标题
二甲基硅烷醇基团改性双三环(D3R)型笼型硅氧烷的合成及晶体结构
DOI：
10.1039/c8dt04244f
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发表时间：
2019
影响因子：
4
通讯作者：
Kuroda Kazuyuki
中科院分区：
文献类型：
--
作者：
Sato Naoto;Tochigi Kazuma;Kuroda Yoshiyuki;Wada Hiroaki;Shimojima Atsushi;Kuroda Kazuyuki
分子构件的受控组装使得纳米材料的合理设计成为可能。在这项研究中，两种具有双三环（D3R）结构的笼型低聚硅氧烷被二甲基硅烷醇基团修饰以形成超分子组装体。一种是源自 Si(OEt)4 的硅氧烷笼（表示为 Q6 笼），另一种是源自 (EtO)3Si–CH2–Si(OEt)3 的有机硅氧烷笼（表示为 T6 笼）。硅烷醇改性笼的合成分两步进行：(i) Q6 和 T6 笼上角 Si-O− 基团的二甲基甲硅烷基化以引入 Si-H 基团，以及 (ii) 随后将 Si-H 基团氧化为 Si-OH 基团。笼的二甲基硅烷化反应在比传统硅烷化反应低得多的温度下进行（Q6和T6笼分别为-94和-78°C），这是抑制不稳定的D3R结构恶化的关键。随后 Si-H 基团的氧化成功进行，并且这些分子的结晶是由硅烷醇基团的氢键诱导的。二甲基硅烷醇基修饰的Q6笼的晶体结构可视为层状结构，层间有四氢呋喃。相比之下，用二甲基硅烷醇基团修饰的 T6 笼组装形成更致密的结构，不含溶剂分子。晶体结构之间的差异根据笼的形状进行讨论。深入了解笼的形状对其组装行为的影响将导致基于结晶硅氧烷的材料的可设计合成。
The controlled assembly of molecular building blocks enables the rational design of nanomaterials. In this study, two types of cage-type oligosiloxanes with double-three ring (D3R) structures are modified with dimethylsilanol groups to form supramolecular assemblies. One is the siloxane cage derived from Si(OEt)4 (denoted as the Q6 cage), and the other is the organosiloxane cage derived from (EtO)3Si–CH2–Si(OEt)3 (denoted as the T6 cage). The syntheses of the silanol-modified cages are performed in two steps: (i) dimethylsilylation of the corner Si–O− groups on the Q6 and T6 cages to introduce Si–H groups and (ii) subsequent oxidation of the Si–H groups to Si–OH groups. Dimethylsilylation of the cages is conducted at much lower temperatures (−94 and −78 °C for Q6 and T6 cages, respectively) than those used for conventional silylation, which is the key to suppressing the deterioration of the unstable D3R structure. The subsequent oxidation of the Si–H groups proceeds successfully, and the crystallization of these molecules is induced by the hydrogen bonds of the silanol groups. The crystal structure of the Q6 cage modified with dimethylsilanol groups can be regarded as a layered structure with tetrahydrofuran between the layers. In contrast, the T6 cage modified with dimethylsilanol groups assembled to form a more densely packed structure with no included solvent molecules. The differences between the crystal structures are discussed in terms of the shape of the cages. The insight into the effect of the shape of the cage on its assembly behavior will lead to the designable synthesis of crystalline siloxane-based materials.