Functionalized dendrons

Figure 7.5 Hybrid copolymers with functionalized dendrons and their assembly on a surface...

Daniel et al. have also reported on the use of thiol-functionalized dendrons as stabilizers for the synthesis of NCDs of about 2.1 nm. The synthetic procedure... 

Fig. 6.7 Convergent covalent attachment of - inert or functional - dendrons during dendrimer construction.

As for the exodendrally functionalized dendrimer catalysts (Sect. 3.2), chiral diamine ligands have also been the objects of study in the investigation into the catalytic behaviour of core-functionalized dendrons. 

Protection of the peripheral phenolic groups as benzyl ethers was selected so that regioselective cleavage of these ethers in the presence of interior aliphatic ether linkages could be effected to liberate phenolic groups at some later stage. These functionalized dendrons were coupled to various anchor cores to produce... 

Similarly, Frechet et al. [102a] utilized a benzyl bromide functionalized dendron, 51, (generation = 3) as a reagent which was then divergently coupled to the tri-valent phenolic, anchoring core, 52, to give the tri-dendron, 53, shown in Scheme 19. 

S. Chavan, W. Maes, J. Wahlen, P. Jacobs, D. De Vos, W. Dehaen, Benzimidazole-functionalized dendrons as molybdenum supports for selective epoxidation catalysis, Catal. Commun. 6 (2005) 241. 

A variety of metal acetylide-containing stars and dendrimers have been synthesized.329-332 Dendrimer 280 was prepared via reaction of a chloro-substituted platinum complex 278 with ethynyl functionalized dendron 279 in the presence of Cul (Scheme 2.73).329 This method generated dendrimers with up to 45 platinum units. 

Another interesting approach to the synthesis of metal-duster core dendrimers involves the displacement of the acetonitrile ligand from the rhenium duster dication [Re6Se6(NCMe)6] with pyridyl-functionalized dendrons. The resultant structures 8.9 possess a hexanudear cluster core and exhibit electronic transitions that are very dependent on the structure of the dendrons [29]. 

Figure 17 Tapping-mode AFM images of two individual azide-functionalized dendronized polymers moved toward each other ( move a->-b, irradiated by UV light), connect (b c), and challenged mechanically ( prove d-f). The arrows indicate the movement of the AFM tip during manipulation. From Barner, J. Mallwitz, F. Shu, L etal. Angew. Chem. 2003,115,1976-1979 Figure 2.

The Staudinger reaction has also been employed for synthetic purposes other than the preparation of iminophosphoranes. Thus, reactions between appropriate k -phosphorus azides and phosphines gave the amine functionalized dendron (68) that could be grafted onto a tetraphosphorus macrocycle with four pendant P-N=P(C6H5)2(p-C6H4-CHO) groups in order to obtain the expected topologicaly amplified compound as a mixture of diastereoisomers. ... 

Supramolecular Assembly of Dendrimers Based on Focal Point Functionalized Dendrons... 

Figure 12 Self-assembly of focal point functionalized dendrons around metal cations according to Fr chet et al.

Later extensions of this general concept were reported by Chapman et al. [169] and Frechet [54] wherein, they reversed the amphiphilic components to produce a functionalized dendron possessing a hydrophobic head and a hydrophilic tail. The Chapman dendritic amphiphiles were derived from alky lene oxide tails and BOC terminated, Denkewalter-type dendritic heads. The Frdchet amphiphiles were obtained by attaching poly(ethylene oxide) to the focal point of a hydrophobic poly(ether) dendron as illustrated in Figure 21 [170,171]. 

One of the most comprehensive examinations of dendritic nanoscale amphiphiles involved structures that mimicked traditional surfactants. This work was reported in a thesis by van Hest et al. [126] [166]. In this study, extensive hydrophobic tails were precisely constructed by the living anionic polymerization of styrene, followed by termination with a primary amine function. Dendronization of these amine functionalized poly(styrenes) produced focal point functionalized, hydrophobically substituted PPI dendrons, as illustrated later (Figure 23). More specifically, the living polystyrene anion is terminated with ethyleneoxide, thus providing a hydroxyl terminated poly(styrene) with... 

Synthesis and Characterization of Carborane Functionalized Dendronized Polymers as Potential Boron Neutron Capture Therapy Agents... 

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