Remarkable difference in catalytic performance of an organoamino-functionalized MCM-41–HPA composite with controlled site-isolation and site-aggregation

The organoamino-functionalized mesoporous silicas with different distribution patterns—site-isolation or site-aggregation are prepared using post-grafting method. We have investigated the effects of the solvents and the catalytic reactivity of these catalysts. It is found that, using the polar ethanol as solvent, the catalytic center is site-isolated. Contrarily, the catalytic center is site-aggregated with the non-polar toluene. Characterization techniques, including transmission electron microscopy, nitrogen sorption experiments, thermogravimetric analysis, and ultraviolet–visible absorbance spectroscopy, demonstrate the most important dependencies of the distribution pattern on the polarity of solvent.