Diffusion-based deprotection in mesoporous materials: A strategy for differential functionalization of porous silica particles
Diffusion-based deprotection in mesoporous materials: A strategy for differential functionalization of porous silica particles
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DOI：
10.1021/ja070598b
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发表时间：
2007-08-08
影响因子：
15
通讯作者：
Landry, Christopher C.
中科院分区：
文献类型：
--
作者：
Cheng, Kai;Landry, Christopher C.
制备了一种单分散的球形介孔二氧化硅(APMS)，并用两种不同链长的Fmoc端基硅烷对其进行了官能化。N-2物理吸附实验表明，在一定条件下，Fmoc保护的有机硅烷完全填充了固体的孔道。然后用哌啶溶液裂解Fmoc基团，使这些堵塞的毛孔“重新开放”。与溶液反应相比，孔内的这种去保护反应要慢得多。UV/可见光光谱分析表明，Fmoc释放速率随时间变化呈S型曲线。实验结果表明，该反应受哌啶溶液的浓度、温度以及孔内Fmoc基团数目的影响。利用这些信息，我们证明了去保护反应在二氧化硅孔隙中的位置是可以经验控制的。我们的工作提供了一种方法，通过这种方法，多孔二氧化硅的表面可以以一种明确的方式进行官能化。这种方法可用于生产催化或药物输送材料。
A monodisperse, spherical mesoporous silica (Acid-Prepared Mesoporous Spheres, APMS) was prepared and then functionalized with two types of Fmoc (9-fluorenylmethyloxycarbonyl) terminated silanes with variable chain lengths. N-2 physisorption experiments indicated that, under some conditions, the pores of the solid were completely filled by the Fmoc-protected organosilanes. These blocked pores were then "reopened" by the cleavage of Fmoc groups with a piperidine solution. In contrast to the solution reaction, this deprotection reaction was much slower within the pores. The rate of deprotection was followed by UV/visible spectroscopy, and a plot of Fmoc released versus time showed a sigmoidal shape. An empirical model was applied to the data, which indicated that the reaction was influenced by the concentration and temperature of the piperidine solution as well as the number of Fmoc moieties within the pores. Using this information, we show that the location of the deprotection reaction in the pores of the silica can be empirically controlled. Our work provides a method by which the surface of the porous silica can be functionalized in a well-defined manner. This method can be used to produce materials for catalysis or drug delivery.