Table I.

The Different Structural Regions of Mesostructured Silicates and Techniques for Derivatization

Structural region	Method of derivatization	Description of method	Examples of utility
Framework	Bonding	Active molecules themselves form a part of the silica framework. They undergo hydrolysis and condensation during synthesis to become incorporated into the final framework.	Placement of photoactive and electroactive metal complexes for energy and electron transfer.
Organic	Philicity	The local solubility of the active molecules determines their placement. Hydrophobic molecules assemble into the micelle interior during synthesis	Placement of pyrene to probe micelle formation; placement of acceptor molecules for energy and electron transfer.
Ionic interface	Bifunctional	An active molecule is chemically bonded to the outside of the framework. The active molecule usually contains one end that is a trialkoxysilane capable of bonding to the framework, and the other end that is hydrophobic.	Placement of azobenzene-based nanoimpellers.
Exterior surface	Postsynthetic grafting	The exposed surfaces are derivatized after synthesis by treating the material with a molecule capable of reacting with silica.	Placement of nanovalves and snap-tops.