A Generic Synthesis Route for Matrix Assisted Self-Assembly of Metal-Oxo Clusters in Organosilica Sol-Gels

The use of an organically modified silica sol-gel matrix containing ligating groups that assist in the formation of metal-oxo clusters is described. The metal-ligand interactions can be tuned by change in external environment such that: a) under overload metal ion concentrations, the sol-gel matrix sequesters the metal ions to promote the growth of 4-7 nm size metal-oxo clusters within the porous structure of the matrix, b) a change in pH releases the metal ions from the bound metal-oxo clusters, thereby making the sol-gel matrix behave as ferritin analogues. These characteristics of the matrix assisted self-assembly of metal-oxo clusters are shown using UVVis, TEM, AES, and EDX data.