Dendrimer carbohydrate-coated

Fig. 1 Carbohydrates in dendrimers Carbohydrate-coated (a), carbohydrate-centered (b) and carbohydrate-based (c).

As shown below in Section 4.1.9 (silicon-based dendrimers), there are meanwhile many examples of carbohydrate-coated dendrimers (glycodendrimers) [48], not least because these terminal groups confer better solubility upon the molecules because they are, so-to-speak, sugar coated . 

FIGURE 16.2 Molecular structures of different glycodendrimers. (a) A carbohydrate-coated dendrimer with 24 pendant monosaccharide residues, (b) A carbohydrate-centered dendrimer with a p-cyclodextrin ((3CD) core and 14 copies of a glycosyl thiol residue, (c) A (1-D-glucosamine-based glycodendrimer comprising 16 monosaccharide residues arranged around a tetravalent polyphenylene core. 

Credi, Raymo and coworkers reported in 2002, the preparation of a new type of carbohydrate-coated, dendronized ferrocenes [46], The structures of these den-drimers are illustrated by compounds 14 and 15. Binding interactions with p-CD were investigated by liquid secondary ion mass spectrometry, 11 NMR spectroscopy, voltammetry and circular dichroism. Upon addition of P-CD, cyclic voltammetric experiments showed data similar to those obtained with our dendronized ferrocenes, that is, a CD-induced current level decrease and anodic half-wave potential shift. At 22°C, these authors obtained K values of 2,000 200 and 1,300 200 M-1 for the complexation of 14 and 15, respectively, by p-CD in 0.1MNaClO4. Similar dendrimers in which carbohydrate branches are covalently attached to both cyclopentadienyl rings of the ferrocene residue were not bound at all by P-CD, reflecting the shielding of the core ferrocene center in these more symmetric compounds. 

This review is devoted to the description of synthetic strategies for glycodendrimers synthesis. Dendrimers can be classified into three categories carbohydrate-coated, carbohydrate-centered and carbohydrate-based dendrimer. In this paper we will focus on the third one, in which the core unit is originated from a monosaccharide. Compare to classical Pamam, Boltorn cores, carbohydrate units add much more three dimension information, coded in the chirality in almost each carbon. Various coupling chemistry have been developed and are presented here glycosylation, amide bound formation, and click chemistry (thiol-ene reaction, epoxide - thiol reaction). 

Glyco-coated dendrimers possess a core structure of varied chemical nature, with a number of peripheral groups to which carbohydrate moieties are attached. The most common core structures are based on polyaminoamides (PAMAM) or poly(propyleneimine) (Astramol ) with a primary amine at the periphery, and these are commercially available. Polyamides based on N,N-bis(3-aminopropyl)glycine and A,Ar-bis(3-aminopropyl)succinic acid have also been prepared.78... 

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