Ligand Characterization of Covalently Functionalized Mesoporous Silica Nanoparticles: An NMR Toolbox Approach

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• 作者：Sean E. Lehman ; Yulia Tataurova ; Paul S. Mueller ; S. V. Santhana Mariappan ; Sarah C. Larsen
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：December 26, 2014
• 年：2014
• 卷：118
• 期：51
• 页码：29943-29951
• 全文大小：318K
• ISSN：1932-7455

文摘

Mesoporous silica materials are undergoing rapid development for numerous environmental and biomedical applications. These materials are commonly functionalized with small organic molecules through a reaction between an organosilane and the surface silanols. Despite widespread use and implementation of these materials, ligands on their surfaces are challenging to characterize, particularly in aqueous environments. Employing traditional physicochemical characterization methods such as adsorption isotherms, X-ray diffraction, and electron microscopy, as well as solution-phase ¹H NMR methods including one-dimensional NMR, diffusion ordered spectroscopy (DOSY) and two-dimensional nuclear Overhauser effect spectroscopy (NOESY), the labile nature of several different surface ligands on mesoporous silica nanoparticles is revealed. The data presented indicate a dynamic model of organosilane release from the surface, and adsorption of the released molecules is ultimately dependent on the nature of the binding of the functional group to the particle surface. A new paradigm for understanding chemical changes that take place at the liquid鈥搒olid interface is described, which incorporates a model of chemical dynamics in aqueous solution. Covalently functionalized nanomaterials are widely used, and the characterization of the ligands on their surfaces is of paramount importance, particularly when they are implemented in biomedical and environmental applications.