Synthesis and characterisation of (hydroxypropyl)-2-aminomethyl pyridine containing hybrid polymer–silica SBA-15 materials supporting Mo(vi) centres and their use as heterogeneous catalysts for oct-1-ene epoxidation

Abstract

Hybrid organic–inorganic amino alcohol containing PGMA–SBA-15 materials have been prepared by first tethering poly(glycidyl methacrylate) (PGMA) chains onto the surface of SBA-15 materials using the atom transfer radical polymerization (ATRP) technique. The procedure involves the functionalization of silica-based SBA-15 materials with aminopropyl groups and 2-bromo-2 methylpropionyl bromide to form ATRP initiator species. Subsequent graft ATRP of glycidyl methacrylate leads to a large decrease of the textural properties in the final material, but nevertheless, the use of the ultra large pore SBA-15 support is beneficial for the achievement of porous hybrid organic–inorganic materials. Reaction of the glycidyl pendant groups in the tethered PGMA chains with 2-aminomethyl pyridine allows the formation of the (hydroxypropyl)-2-aminomethyl pyridine ligands to which molybdenum(VI) species catalytically active for epoxidation of terminal alkenes are bound. The materials thus prepared display high catalytic activity and excellent stability and reusability in the epoxidation of 1-octene with TBHP as oxidant. The presence of mesoporosity in the final Mo(VI)-containing hybrid materials boosts the catalytic activity of supported metal centres.