Synthesis of organic-inorganic hybrids via the non-hydrolytic sol-gel process

In its most common form, the non-hydrolytic sol-gel (NHSG) process involves the reaction of a "metal" halide with an oxygen donor, leading to the formation of an inorganic oxide. The use of NHSG chemistry for the synthesis of organic-inorganic hybrids is in its infancy compared to progress on hybrid synthesis using hydrolytic sol-gel chemistry. To date, most work has been carried out on the synthesis of organically modified inorganic oxides such as ormosils, with very limited effort on oxide-polymer hybrids and no reported activity on incorporation of small organic molecules into oxide networks. In this paper, reports of the use of the NHSG route to synthesize hybrids are reviewed. The key features of the reaction chemistry are noted, along with a discussion of the scope and limitations of NHSG chemistry in comparison with the hydrolytic route. Promising areas for future study are proposed, together with potential applications of these hybrids.