Guest inclusion by steric compression

Thanks to their conformational flexibility, POPAM dendrimers can serve as host molecules for small guest molecules. The non-covalent reversible inclusion of these guests is attributable to electrostatic, hydrophobic, H-bonding, and acid/ base effects in the interior of the dendrimer. 

However, irreversible inclusion can be accomplished through formation of a dendritic box by steric compression of the periphery (Fig. 6.16) - after covalent coupling to a sufficient number of large terminal groups. For the inclusion of dye molecules in such dendrimers, see also Section 8.3.6. 

The possible formation of niches can also be exploited for the catalysis of chemical reactions. Palladium nanoparticles of 1.7-nm diameter included in a 

---