Strategies for Localizing Multiple Functional Groups in Mesoporous Silica Particles through a One-Pot Synthesis

The process of postcondensation for the functionalization of mesoporous silica is based on the cooperation between the end-on growth of arrays of silica nanochannels and the steric hindrance of the functional silanes (R-silanes). To obtain particles with differently functionalized surfaces (thiol and amino groups), the delayed addition of another R-silane was introduced. This tandem postcondensation approach allows for three selective functionalization strategies, depending on the mobility and the steric hindrance of the R-silanes. Following these one-pot synthesis strategies, functional groups can be placed independently on the pore entrances and on the internal surface of the mesoporous silica particles. Confocal laser scanning microscopy was used to image the functional group distribution after selective coupling with a fluorescent dye. Nitrogen sorption measurements were conducted to confirm the well-defined mesoporosity of the functionalized products.