Amide-based dendrimer

Figure 2.8. Solvent accessible surface areas calculated for a second generation amide-based dendrimer using probes with increasing radii.

Figure 2.13. Determination of the fractal dimension (D — 2.40 and D = 2.43) for 3rd (top) and 4th (bottom) generation amide-based dendrimers. [See the table presented in Figure 2.8]...

Scheme 5.36. Construction of jV-benzyl terminated amide-based dendrimers...

Acid-terminated, amide-based dendrimers (i.e., 31) have been shown to be effective surfactant substitutes in... 

Feast et alJ68-70al reported the convergent construction of a series of aromatic polyamide dendrimers exactly analogous to the amide-based macromolecules described by Miller and NeenanJ3 The synthetic transformations employed for wedge construction were also similar except that reduction of the aromatic nitro group was effected by treatment with NaBFL and SnC -I O instead of catalytic reduction (see Scheme 5.22). 

Dendrimers can be reacted with a variety of compounds to further functionalize them to give them unique characteristics. For example, amine-terminated dendrimer can be reacted with imsaturated nitriles to give a polynitrile dendrimer. In another case the polyamine dendrimer can be reacted with jS-unsat-urated amides to give amide-terminated dendrimer. A whole host of possibilities can be visualized based on the reactivity of the amino group [43]. 

C-branched dendritic structures, based on either ether and amide linkages or simply amide connectivity (iii) Tomalia-type PAMAM dendritic structure, differing from the POPAM by the presence of amide bonds, but keeping the amine AB2 as the branching center and (iv) Fr6chet-type dendritic strnctures, based on ether and phenyl groups as AB2 branching center. Description of the different types of covalent dendrimers reported will follow a classification based on the element content, such as only C, C-N, N-O, C-N-0, or with heteroatoms such as P, Si, and so on. Examples of porphyrin-, thiophene-, carbohydrate-, and fullerene-based dendrimers are described separately, since they can be bound to different types of frameworks. 

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). 

Other supramolecular structures such as dendrimers have also been synthesized with zinc-containing porphyrins. Sixteen free base and sixteen zinc porphyrin units were added at the fifth generation of dendritic poly(L-lysine) and intramolecular fluorescence energy transfer was observed.823 Assembly of supramolecular arrays in the solid state has been achieved with the incorporation of an amide group for hydrogen bonding. Zinc meso-tetra(4-amidophenyl)porphyrin... 

For the synthesis of perfectly dendronized sohd-phase polymers (Fig. 7.4) various dendritic structures were prepared based on amide connections [6]. For example, the naturally occurring amino acid lysine was used as a building block in creating a dendritic scaffold [33]. The synthesis of symmetrical tri-branching den-drimers on aminomethyl polystyrene macrobeads was also described in literature [34]. Recently, aryl ether dendrimers were prepared on hydroxymethyl polystyrene using a Mitsunobu reaction with 3,5-bis(acetoxymethyl)phenol [35]. 

Kaneda et al. [33,34] have recently utilized acid-base interactions to non-covalently attach diphenylphosphine-4-benzoic acid palladium complexes to the exterior of poly(propyleneimine) dendrimers and to cavities within these dendrimers (Fig. 9) via the interaction of the benzoic acid with the carboxyl groups of amide moieties positioned within the dendrimer. Interestingly, the supramolecular dendritic catalyst gave rise to much more active catalysts for... 

Approximately six years after Denkewalter s patent, two new architectures were published in 1985. Newkome et al. 41 relied on triester amidation with tris for the construction of polyols (8) possessing maximal 1 — 3 C-based branching. Repetition of the sequence was precluded by surface steric inhibition towards nucleophilic substitution. Tomalia et al. 42a reported the preparation of an entire series of dendrimers (9, up to the 7th tier) possessing trigonal, l—>2 N- based, branching centers. To date, availability has... 

Dendrimer 3 (Fig. 7), which is based on a benzene core branched in the 1, 3, and 5 positions, contains 18 amide groups in its branches and 24 chromophoric dansyl units in the periphery. It is well known that, in sufficiently basic solution, amide groups (25), including the dansylamide units (25) can undergo deprotonation and coordination of transition metal ions. The dansyl units show strong absorption bands in the near UV... 

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