Grafting of nitroxyl (TEMPO) radical on the surface of silical gel and micelletemplated silica (MTS)

摘要

Grafting of TEMPO on MCM-41-type silica (MTS) and on silica gel was achieved through amide bond on previously grafted amino chains by two different procedures. The spin labeling materials were characterized by various physicochemical methods (XRD, nitrogen sorption volumetry, thermogravimetry, IR, NMR, EPR and UV-Vis spectroscopies). The main conclusion drawn from UV-Vis spectroscopic studies on reaction of TEMPOimmobilized species with electron-acceptor properties is that functionalization of mineral support through coupling reaction on previously anchored organic chains would not necessarily lead to fully grafted species. Special attention should be focused on the control of anchoring in immobilized catalysts.