Department of Chemistry, Graduate School of Science, Kyoto University , Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan.
Langmuir. 2013 Oct 1;29(39):12243-53. doi: 10.1021/la402205j. Epub 2013 Aug 26.
Synthesis of class II hybrid silica materials requires the formation of covalent linkage between organic moieties and inorganic frameworks. The requirement that organosilylating agents be present to provide the organic part limits the synthesis of functional inorganic oxides, however, due to the water sensitivity and challenges concerning purification of the silylating agents. Synthesis of hybrid materials with stable molecules such as simple alcohols, rather than with these difficult silylating agents, may therefore provide a path to unprecedented functionality. Herein, we report the novel functionalization of silica with organic alcohols for the first time. Instead of using hydrolyzable organosilylating agents, we used stable organic alcohols with a Zn(II) catalyst to modify the surface of a recently discovered highly reactive macro-mesoporous hydrogen silsesquioxane (HSQ, HSiO1.5) monolith, which was then treated with water with the catalyst to form surface-functionalized silica. These materials were comprehensively characterized with FT-IR, Raman, solid-state NMR, fluorescence spectroscopy, thermal analysis, elemental analysis, scanning electron microscopy, and nitrogen adsorption-desorption measurements. The results obtained from these measurements reveal facile immobilization of organic moieties by dehydrogenative addition onto surface silane (Si-H) at room temperature with high loading and good tolerance of functional groups. The organic moieties can also be retrieved from the monoliths for recycling and reuse, which enables cost-effective and ecological use of the introduced catalytic/reactive surface functionality. Preservation of the reactivity of as-immobilized organic alcohols has been confirmed, moreover, by successfully performing copper-catalyzed azide-alkyne cycloaddition (CuAAC) "click" reactions on the immobilized silica surfaces.
合成 II 类杂化硅材料需要在有机部分和无机骨架之间形成共价键。然而，由于有机硅试剂的水敏性和纯化方面的挑战，需要有机硅试剂来提供有机部分，这限制了功能无机氧化物的合成。因此，用稳定的分子（如简单醇）而不是这些难以硅烷化的试剂来合成杂化材料，可能为提供前所未有的功能提供了一条途径。在此，我们首次报道了首次用有机醇对硅进行的新型功能化。我们没有使用可水解的有机硅试剂，而是使用稳定的有机醇和 Zn(II)催化剂来修饰最近发现的高反应性大孔介孔硅烷（HSQ，HSiO1.5）单体，然后用催化剂处理水以形成表面官能化的硅。这些材料用 FT-IR、拉曼、固态 NMR、荧光光谱、热分析、元素分析、扫描电子显微镜和氮气吸附-解吸测量进行了全面表征。这些测量结果表明，通过在室温下通过脱氢加成将有机部分容易地固定在表面硅烷（Si-H）上，具有高负载量和良好的官能团耐受性。还可以从单体中回收有机部分以进行回收和再利用，这使得引入的催化/反应性表面功能具有成本效益和生态效益。此外，通过成功地在固定化的硅表面上进行铜催化的叠氮-炔环加成（CuAAC）“点击”反应，还证实了所固定的有机醇的反应性得以保留。
