Sol-gel synthesis of phosphates

Phosphate and silicate materials exhibit similar structures but their solution chemistry is very different. Polyphosphates cannot be synthesized under ambient conditions from PO(OR)3 or PO(OH)3 solutions. More convenient PO(OH)3−x(OR)x precursors have been obtained via the dissolution of P2O5 in alcohols. Their reactivity towards hydrolysis and condensation depends on x and the alkyl group. They have been used as precursors for the sol-gel synthesis of titanium phosphates. 31P NMR experiments show the formation of P-O-Ti bonds during the course of the reactions.