Host-guest chemistry of dendritic macromolecules

A very important question in the context of dendrimers and their utility as host molecules relates to the existence of cavities within these macromolecules. The presence of internal voids in dendrimers is closely related to their conformational behaviour and to the degree of back-folding of the terminal branches into the interior of the dendrimer. The issue of back folding was already briefly touched upon in section 16.2.1. Next to the purely theoretical calculations mentioned there, several calculations have been performed on specific dendrimer types. 

Murat and Grest performed a molecular dynamics study on PAMAMs in 

Poly(benzyl ether) dendrimers synthesized by Frechet el al. have been studied with many techniques in order to reveal their conformational properties. Size exclusion measurements performed by Mourey et al. [154], rotational-echo double resonance (REDOR) NMR studies by Wooley et al. [155] and spin lattice relaxation measurements by Gorman et al. [156] reveal that back-folding takes place and the end-groups can be found throughout the molecule. The observed trends are in qualitative agreement with the model of Lescanec and Muthukumar [54], 

---