Chemical modification of titanium alkoxides for sol-gel processing

The chemical modification of titanium alkoxides by alkoxy- and aminoalcohols, beta-diketones, beta-ketoesters, carboxylic and phosphonic acids, and related compounds, and the hydrolysis behavior of the organically modified precursors are reviewed. Special focus is put on structural aspects and on the possibility to introduce functional organic groups. Such precursors have a high potential for innovative materials syntheses because they permit control of the precursor reactivity in sol-gel processes and the preparation of titania-based inorganic-organic hybrid materials. Coordination, solvation, aggregation and redistribution equilibria play an important role in the chemistry of the modified titanium alkoxides, and organic side reactions have to be taken into account.