5/-based dendrimers

Figure 24 Phosphine-based dendrimers prepared from T8[CH = CH2]8 and used in the hydroformylation reaction.

Perrier RJ (2001) Direct Conversion of 5,6-Unsaturated Hexopyranosyl Compounds to Functionalized Glycohexanones. 215 277-291 Frey H, Schlenk C (2000) Silicon-Based Dendrimers. 210 69-129 Forster S (2003) Amphiphilic Block Copolymers for Templating Applications. 226 1-28 Frullano L, Rohovec J, Peters JA, Geraldes CFGC (2002) Structures of MRI Contrast Agents in Solution. 221 25-60... 

Ferrier RJ (2001) Direct Conversion of 5,6-Unsaturated Hexopyranosyl Compounds to Functionalized Glycohexanones. 215 277-291 Frey H, Schlenk C (2000) Silicon-Based Dendrimers. 210 69-129... 

Moore et al. later reported [98] the design and synthesis of triarylamine based dendrimers. These fluorescent macromolecules exhibited reversible redox processes and their potential use in electro-optic film applications was envisioned. 

Solvatochromic probes have been used for a variety of applications like the study polarity of pure and mixed solvents [99], and the retention behavior in reverse-phase liquid chromatography [100] among other applications. Frechet et al. used 4-(N-methylamino)-l-nitrobenzene (p-MANB), as the chromophore, to probe the microenvironment of polyaromatic ether based dendrimers [101]. 

For instance, some time ago Newkome et al. reported the synthesis of ruthenium based dendrimers [170]. A dendrimer (80) with twelve peripheral terpyridine ligands was built around a central quaternary carbon-based core. In the final step complexation between the terminal ligand of the dendrimer and a terpyridinyl ruthenium chloride building block afforded the dodecaruthenium cascade molecule 80 (Fig. 35). Thus, preconstructed cores and dendritic fragments were linked by Ru2+ as the connecting unit and this mode of connectivity could be denoted by [—(Ru)—]. 

Dubois et al. [184] reported the synthesis of phosphorus based dendrimers terminated with multivalent palladium complexes. Iterative free radical addition... 

Complexation of gold ions, [Au(I)], with peripheral phosphine groups of a P-based dendrimer was reported by Majoral et al. [185]. Transmission electron microscopy (TEM) was used to analyze the large aggregates formed by the dendritic gold complexes and a direct correlation was observed between the size of the particles and the dendrimer generation number. In a recent report [186], Majoral et al. further demonstrated that up to 48 diphosphino groups could be anchored to the surface of dendrimers and various dendritic metal-complexes... 

Keywords. Metal-based dendrimers, electrochemistry, multielectron processes, luminescence, light harvesting. 

Polynuclear complexes based on octahedral building blocks may be structurally not well defined because of stereogenic problems [8]. However, clever synthetic strategies have recently been devised to obtain chirally pure species [61-65]. Synthesis and, of course, photophysical and photochemical studies of stereochemically pure metal-based dendrimers are still in their infancy. 

The first photophysical investigation performed on stereochemically pure metal-based dendrimers having a metal complex as the core is that concerning the tetranuclear species based on a [Ru(tpphz)3]2+ core (tpphz=tetrapyrido[3,2-a 2, 3 -c 3",2"-h 2",3"j]phenazine) [67]. Dendrimer 45 is an example of this family. In this compound, two different types of MLCT excited states, coupled by a medium- and temperature-dependent photoinduced electron transfer, are responsible for the luminescence behavior. However, the properties of all the optical isomers of this family of compounds are very similar. This finding is also in... 

R. Roy, D. Zanini, S. J. Meunier, and A. Romanowska, Syntheses and antigenic properties of sialic acid-based dendrimers, in P. Kovac, (Ed.), Synthetic Oligosaccharides Indispensable Probes for the Life Sciences, ACS Symp. Sen, 560, 1994, pp. 104-119. 

B. W. Greatex, S. J. Brodie, R. H. Fumeaux, S. M. Hook, W. T. McBumey, G. F. Painter, T. Rades, and P. M. Rendle, The synthesis and immune stimulating action of mannose-capped lysine-based dendrimers, Tetrahedron, 65 (2009) 2939-2950. 

Son, D. Y. Silicon-Based Dendrimers and Hyperbranched Polymers. In Chemistry of Organic Silicon Compounds-, Rappoport, Z., Apeloig, Y., Eds. Wiley Chichester, 2001 Vol. 3, pp 745-803. 

Another example of hypermonomer-based dendrimer synthesis was reported by Gilat et al. for the rapid preparation of a new family of laser dye-labeled dendrimers that were critical to our study of energy transfer in light harvesting dendrimers (Scheme 6) [29]. In order to avoid undesirable through-bond energy transfer in the poly(benzyl ether dendrimers, the reversed monomer unit,... 

One of the first results on the use of phosphine dendrimers in catalysis was reported by Dubois and co-workers [16]. They prepared dendritic architectures containing phosphorus branching points which can also serve as binding sites for metal salts. These terdentate phosphine-based dendrimers were used to incorporate cationic Pd centers in the presence of PPh3. Such cationic metalloden-dritic compounds were successfully applied as catalysts for the electrochemical reduction of C02 to CO (e.g. 9, Scheme 9) with reaction rates and selectivities comparable to those found for analogous monomeric palladium-phosphine model complexes suggesting that this catalysis did not involve cooperative effects of the different metal sites. 

Beside these catalytically active metallophosphine dendrimers (see above), preliminary studies on the chemical properties of phoshorus-based dendrimers complexed to metals such as platinum, palladium and rhodium have been described by Majoral, Caminade and Chaudret [21], They showed that these macromolecules (see Scheme 13) could be useful for the (in situ) generation of metallodendrimer catalysts. 

Organometallic chemistry, in particular the chemistry of ferrocenes, is affording significant contributions to the field. As illustrated in Figure 28, ferrocene-based dendrimers can assume compositions ranging from a single ferrocene unit properly functionalized45 to multiferrocene units placed in the outer zone of the surface.46... 

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