Optimization of Reaction Conditions for the Metalorganic Modification of MCM-41

The modification of periodic mesoporous silica with organic groups following an optimized metalorganic route is described. Organolithium and Grignard reagents (n-butyllithium and allyl-magnesium bromide) were used to directly substitute silicon atoms with organic moieties in the channel walls of the silica host. A detailed study of several representative reactions with respect to reaction parameters, that is, reaction temperature, reaction time, and reagent concentration, shows that the degree of surface substitution can be controlled within a broad range and up to very high levels while still maintaining the integrity of the ordered silica host. The functionalized mesoporous materials can also retain high surface areas and pore volumes. Furthermore, the reactions can be performed at low temperatures compared to the more traditional grafting techniques on the basis of organosilanes.