期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 113, 期 24, 页码 10667-10674出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp901983j
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资金
- European Commission [MRTN-CT-2006035884]
- Swiss National Science Foundation [200020-117591]
The accessibility of amino groups in postsynthetically functionalized mesoporous silica MCM-41, MCM-48. and SBA-15 is investigated by reaction with fluorescein isothiocyanate (FITC). The quantitative analysis of the surface-grafted amino groups in relation to the amount of coupled FITC over a wide range of loading.,; affords information about potential pore blocking. In the pore diameter domain of 3-4 nm, the actual pore size of materials with a one-dimensional channel system (MCM-41) strongly affects the FITC coupling yield and the distribution of the anchored fluorescein moieties. In the case of SBA-15 (7.6 nm pore diameter), the accessibility of the grafted amino groups is similar to what is expected for a material with a completely open surface. However, grafting in the intrawall micropores of SBA-15 leads to a substantial fraction of inaccessible amino groups. As a direct consequence of short channel lengths and large external surface area, excellent accessibility is also observed for nanometer-sized MCM-41 (3.2 nm pore diameter).
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