Mesostructured Metal Oxides

Mesostructured metal oxides have an open framework structure that repeats on a mesometric length scale (2 - 50 nm) and thereby exhibit Bragg scattering on the same length scale. But the atoms defining the pore walls typically are disordered (amorphous). The supramolecular assembly of mesostructured metal oxides can be achieved through a number of pathways in which electrostatic charge matching interactions, dative bonds, hydrogen bonds and van der Waals forces operate between the structure - directing surfactant and the metal oxide precursor. Depending primarily on the assembly pathway, distinguishable types of structural order/disorder can occur on two length scales. A "long range" order/disorder occurs on a length scale of hundreds of nanometers which affects the framework structure and hierarchical particle shape of the mesostructure. In contrast, "short range" or "local" order/disorder occurs on an atomic length scale and determines the properties of the framework walls. The effects of both types of order/disorder on the physical and chemical properties of representative silica and aluminosilicate mesostructures will be discussed, along with some of their organofunctional derivatives.