Sol-Gel Synthesis of Metal Oxide Clusters and Colloids

Abstract

ABSTRACTThe hydrolysis and condensation of metal alkoxides M(OR)z allows the formation of oxopolymers or oxide colloids under mild conditions in solution. The molecular design of these precursors provides a chemical control over the formation of condensed phases. This can be conveniently performed via the chemical modification of alkoxides by nucleophilic species such as carboxylates or β-diketones. Condensation can be tailored with two chemical parameters; the hydrolysis ratio which leads to more condensed species and the amount of complexation which prevents condensation. Molecular clusters or colloidal particles can be obtained instead of precipitates. Moreover, non hydrolyzable complexing organic ligands lead to the formation of hybrid materials in which organic and inorganic moities are chemically bonded. These hybrid clusters and colloids are important starting points for producing solids and films with novel physical properties.