作者:Katharina Ladewig、Andreas Seifert、Harald Hahn、Michael Hietschold、Norbert Moszner、Peter Burtscher、Stefan Spange
DOI:10.1039/c2jm15407b
日期:——
An advanced procedure for the one-pot synthesis of organicâinorganic hybrid materials via combination of solâgel process and nucleophilic aromatic substitution reaction (SNAr) of 4-fluoronitrobenzene and 3-aminopropyltrimethoxysilane is described. With this advanced procedure both SNAr-reaction and solâgel process can be accomplished in the same reaction vessel due to the solâgel precursor tetraethoxysilane (TEOS) acting as solvent during the first reaction step. Via extensive NMR spectroscopic studies it is proven for the first time thatâcontrary to common beliefâhydrogen fluoride (HF), which is formed as a by-product in the SNAr-reaction, is not trapped by any bases present but is rather trapped by both of the silane species and serves as a catalyst during the subsequent solâgel process. The chromophoric system of the resulting xerogels is well protected against aggressive chemicals, i.e. strong acids, by the silica matrix, which predestines these materials for pigment applications. Given that a high chromophore content is highly desirable in these applications, we show that the chromophore content of the final xerogel can be varied by modification of the organosilicon precursorâ:âTEOS ratio or by using trialkoxy-silanes bearing two or three amino functions, whereby the latter option is more favourable. Monodisperse coreâshell particles with identical chromophore content but consisting of a pure silica-core and a p-nitroaniline functionalized shell with a diameter of about 200 nm can also be prepared using this advanced procedure.
描述了一种通过溶胶凝胶法与 4-氟硝基苯和 3-氨基丙基三甲氧基硅烷的亲核芳香取代反应 (SNAr) 相结合来一锅法合成有机-无机杂化材料的先进方法。通过这种先进的程序,SNAr 反应和溶胶凝胶过程可以在同一反应容器中完成,因为溶胶凝胶前体四乙氧基硅烷 (TEOS) 在第一个反应步骤中充当溶剂。通过广泛的核磁共振波谱研究,首次证明,与普遍看法相反,氟化氢 (HF) 是 SNAr 反应中的副产物,不会被任何存在的碱所捕获,而是会被捕获。相反,它被两种硅烷物质捕获,并在随后的溶胶凝胶过程中充当催化剂。二氧化硅基质很好地保护了所得干凝胶的发色系统免受侵蚀性化学物质(即强酸)的影响,这使得这些材料适合颜料应用。鉴于在这些应用中非常需要高发色团含量,我们表明,最终干凝胶的发色团含量可以通过修改有机硅前体-:-TEOS比率或通过使用带有两个或三个的三烷氧基硅烷来改变。氨基功能,其中后一种选择更有利。使用这种先进的程序也可以制备具有相同发色团含量但由纯二氧化硅核和直径约 200 nm 的对硝基苯胺官能化壳组成的单分散核壳颗粒。