Third-generation dendrimer

The first-generation dendron 29 was grown up to the second- and third-generation dendrons 33 and 34 by the successive reaction with dinuclear platinum complex 32 followed by treatment with TBAF for desilylation (Scheme 11). Reactions of the second- and third-generation dendrons 33 and 34 with the core 30 gave the second- and third-generation dendrimers, respectively. Although... 

Further characterization of the dendrimer-coupled protein complexes was studied by hydrophobic interaction chromatography carried out by purification over an octyl-Sepharose column. The products obtained by reaction of SIAB with ALP and its complex with third-generation dendrimer, ALP-E3, were... 

In water, the third-generation (16) and fourth-generation dendrimers (17) induced chirality toward the (S)-enantiomer (50% ee for 16 and 98% ee for 17). In THF high enantiomeric excess was achieved only with the third-generation dendrimer (99% (S) ee for 16 and 3% (S) ee for 17). Dendrimer 16 was recovered from the heterogeneous reaction mixture by nanofiltration on a Millipore microporous membrane system. After regeneration of the catalytic activity by treatment with... 

The third-generation dendrimer palladium complex (31, containing 24 PdC groups) was applied in the Stille coupling of methyl-2-iodobenzoate with 2-(tributyl-stannyl)thiophene in DMF (Scheme 10 lmol% catalyst). In contrast to what was observed with the monomer (PPh3)2PdCl2, no palladium metal formation was... 

The self-diffusion coefficients were calculated, and the effective radii of the dendrimers were estimated from the diffusion coefficients by assuming a spherical geometiy for all dendrimers. The so-obtained radii were 7.8,10.3, and 12.6 A for the first, second, and third generation dendrimer, respectively. 

First, second, and third generation dendrimers based on THPE (core) and bis-MPA (repeating unit) have been synthesized and characterized. SEC and NMR analyses verified that the dendrimers were monodisperse. Diffusion NMR was used to determine the dendrimers hydrodynamic radii in deuterated chloroform. First, second, and third generation dendrimers were found to be 7.8, 10.3, and 12.6 A, respectively. These were in agreement with sizes as determined from molecular models (Biichi). 

Nierengarten et al. expanded upon their Ceo-based dendrimers to make a series of copper bis-phenanthroline core dendrimers of the form Core3-Rpt3-Periph4.80 In this series, the redox potential of the core did not vary notably with generation, but the kinetics slowed down as the generation increased. The CV wave of the second- and third-generation dendrimers could not be observed. 

For the third-generation dendrimer 26 the first reduction wave is symmetrically bell-shaped and the peak current is proportional to the scan rate (for v < 400 V/s), demonstrating that 26 is adsorbed on the electrode surface. From the area under the peak and the dendrimer area, a bilayer is estimated to be deposited onto the electrode. Upon increasing scan rate (v > 104 V/s), only a fraction of the units are reduced during the forward scan because only part of the fullerene moieties are close enough to the surface to allow direct electron transfer. On the other hand, at lower scan rates, all the fullerene redox sites are accessible and thus they can store charges. 

Dendrimers with a polypropylene imine (PPI) core, decorated with a periphery of 3,4-dialkoxybenzamides with two semifluorinated chains (215, see Fig. 71), show a transition from a Colhex phase for the third generation dendrimer (Cr 76 Colhex 226 Iso) to a micellar cubic phase (Cr 78 Cub 235 Iso) for the fifth generation dendrimer [377]. 

Fig. 71 Examples of PPI based molecular (215) and supramolecular third generation dendrimers (216-217) with fluorinated chains and mixed RF/RH-chains [377-381]...

Masamune and coworkers reported a divergent stepwise synthesis of siloxane dendrimers as shown in Scheme 15155. The third generation dendrimer was the largest obtained. Characterization techniques included 1H, 13C and 29Si NMR spectroscopy, mass spectroscopy and size-exclusion chromatography. 

Compound 2 is a third-generation dendrimer based on a poly(arylether) structure and contains 24 equivalent ferrocenyl units even in this case the potential required for ferrocene oxidation was essentially the same observed in lower-generation analogues [55]. 

Compound 20 is a third-generation dendrimer based on a [Fe(tpy)2] " core (tpy = 2,2 6, 2"-terpyridine) surrounded by a polyether framework [93]. Electrochemical characterization in CH2CI2 or THF of dendrimers of generation 0-3 indicated that the reversibility of both the metal-centered oxidation and of the tpy-... 

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