Pore size control and organocatalytic properties of nanostructured silica hybrid materials containing amino and ammonium groups

Periodic mesoporous organosilicas containing amine and ammonium substructures were synthesized via soft templating approaches using anionic surfactants. Pore size control was achieved either using anionic surfactants containing alkyl groups of variable chain lengths or by addition of swelling agents such as mesitylene (1,3,5-trimethylbenzene, TMB) to the hydrolysis-polycondensation mixture. The addition of mesitylene allows to increase the pore size in the materials from 2 to 6 nm. The materials appear as versatile and recyclable heterogeneous organocatalysts in Knoevenagel and Henry reactions and in the formation of monoglycerides by ring opening reaction of glycidol. This study highlights the huge potential of silica hybrid materials containing ionic substructures (i-silica) materials in heterogeneous catalysis.