Imidazolium-derived organosilicas for catalytic applications

Imidazolium salts are applied in different fields of research and have found a wide variety of applications owing to their distinctive properties. This review exclusively focuses on the various methods (grafting, surfactant-assisted sol-gel synthesis, bridged silsesquioxanes formation) described in recent years for the covalent immobilization of imidazolium salts on silica supports via C-Si bonds and on the catalytic applications of the resulting silica-supported imidazolium salts and NHC complexes. C-C bond formation reactions such as cross-coupling, olefin metathesis or organocatalyzed Knoevenagel condensations as well as functionalization reactions are described. This review is intended to help in inspiring future developments and interest in the growing field of catalysis by supported imidazolium salts and NHC complexes based on organosilicas.