Encapsulating dendrons, generation

As the generation of encapsulating dendrons around a redox-active core increases, the rate of electron transfer decreases. In the section above, many examples conformed with this general model. However, one exception has been illustrated. The cause of this exception is mysterious, however. 

Delivery of physically encapsulated small molecules at targeted sites by dendrimers has been superbly envisioned in a recent report by McGrath and Junge [95]. Second generation Frechet type dendrons linked to a central azo-benzene-derivative (32, Fig. 15) underwent reversible cis/trans isomerization of... 

In aqueous media, they assemble into spherical capsules capable of encapsulating Nile Red with remarkably low CMC values (2 x 10 M for G1 and 3 x 10 M for G2). Similarly, the size of the aggregate derived from a related dendron-rod-dendron copolymer, composed of a phenylene vinylene rod capped on each end by amphiphilic polyether dendrons, could be tuned in the melt state by modifying the generation level of the dendron (Fig. 11.28 Lee et al. 2002). 

The G5 and G6 dendrons did not assemble into monolayers because of the tendency of the focal point to be encapsulated by the hydrophobic dendritic branches at higher generations. Similarly, Liskamp s group reported a series of amino acid based dendrons capped with Boc end groups and a focal fatty acid chain also formed stable monolayers however, the fatty acid group was not a significant improvement over a shorter linkage (Mulders et al. 1998). In the condensed mono-layer phase, the dendrons covered a smaller area than predicted for a fully spread... 

Fig. 14. Dendritic PTA oligomers with the linearly re-conjugated allcarbon backbone encapsulated by dendrons of first to third generation...

Aranishi K, Zhu QL, Xu Q. Dendrimer-encapsulated cobalt nanoparticles as high- performance catalysts for the hydrolysis of ammonia borane. Chem Cat Chem 2014 6 1375-9. Mizugaki T, et al. PAMAM dendron-stabilised palladium nanoparticles effect of generation and peripheral groups on particle size and hydrogenation activity. Chem Commun 2008 241-3. 

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