Sol-gel chemistry

Sol-gel chemistry involves nucleophilic reactions. The chemical reactivity of metal alkoxides toward hydrolysis, condensation and complexation mainly depends on the electronegativity of the metal atom, its coordination number and the steric hindrance of alkoxide groups. Silicon alkoxides are poorly reactive. Hydrolysis and condensation rates have to be enhanced by acid and base catalysis or nucleophilic activation. Transition metal alkoxides are usually too reactive. They have to be stabilized by complexation in order to avoid fast condensation. The molecular design of alkoxide precursors opens the way to tailor-made materials.