Dendrimers and Polymers

Tomalia et al. reported that the surface amines of PAM AM dendrimer can successfully react with methyl esters of other PAMAM dendrimers to afford core-shell tecto-(dendrimer) molecules [65]. Furthermore, they also reported the synthesis of rod-shaped cylindrical dendronized polymers from poly(ethyleneimine) cores without any crosslinking, albeit with the use of excess reagents [58]. These reports lead us to propose a new approach toward hybridized dendrimers and polymers (path C, Figure 15.3). As shown in Scheme 12,... 

In general, silver clusters in solution are prepared by reduction of silver ions. Proper scaffolds, e.g., DNA, proteins, dendrimers and polymers, are essential to prevent the aggregation of clusters to larger nanoparticles. Although it is clear that the emission originates from few-atom silver clusters, many aspects of this exciting class of nanoscopic metals are not yet fully understood. 

Although beyond the scope of this book, a vast amount of work has been directed to supporting homogeneous catalysts on solid supports including silica, alumina and zeolites, and functionalized dendrimers and polymers [19]. These give rise to so-called solid-liquid biphasic catalysis and in cases where the substrate and product are both liquids or gases then co-solvents are not always required. In many ways solvent-free synthesis represents the ideal method but currently solvent-free methods can only be applied to a limited number of reactions [20],... 

S. Thayumanavan ( Thai ) obtained his B.Sc. and M.Sc. degrees from The American College, Madurai, India. He obtained his Ph.D. from the University of Illinois at Urbana-Champaign with Professor Peter Beak in 1996. After a postdoctoral stint with Professor Seth Marder at the California Institute of Technology, he started his independent career at Tulane University in 1999. His group moved to the University of Massachusetts at Amherst in 2003. He has been the winner of NSF-CAREER award, Cottrell Scholar award, and 3M Non-tenured Faculty awards. His research interests involve design and syntheses of macromolecules (dendrimers and polymers) to achieve controllable nanoscale assemblies that are of interest in chemistry, materials, and biology. 

VI. SYNTHESES OF SILICON-CONTAINING DENDRIMERS AND POLYMERS USING HYDROSILYLATION... 

The structure of cationic lipids and polymers is readily amenable to chemical modification [35, 36] allowing the exploration of a virtually unlimited number of combinations and strategies at the mercy of chemists creative abilities. Various reviews have been focused on cationic lipids, dendrimers and polymers in terms of their chemical structures and their transfection properties [36—41], in an attempt to shed some light on the chemical requirements necessary to mediate gene delivery. The focus of this chapter will be to explore these carriers from a synthetic perspective, with a description of the chemical strategies used for the preparation via synthetic organic chemistry (excluding polymer synthesis) of cationic lipids and dendrimers. 

Related optical and fluorescent sensor systems have been widely used. For instance, the fluorescence of the pyrene unit in species (187) is quenched upon saccharide binding to the boron center. Boronic acid groups were also attached to dendrimers and polymers. The benefit of systems containing at least two boronic acid centers, as shown for the luminescent saccharide sensor (187), is that two-point binding can more effectively control saccharide binding. Similar... 

This section has focused on liquid—liquid biphasic catalysis in which catalysts are supported in different solvents to the substrates and products. Considerable efforts have also been directed to supporting homogeneous catalysts on solid supports including silica, alumina, and zeolites as well as functionalized dendrimers and polymers.33 It has also been found that synergic effects sometimes prevail between particles embedded in the support and the tethered molecular catalyst, increasing the activity of the catalyst.34... 

Eor use of dendrimer- and polymer-boimd TiTADDOLates in these cycloadditions, see Seebach D, Marti RE, Hintermann T (1996) Helv Chim Acta 79 1710... 

Dendrimer- and polymer-supported catalysts can be employed in the ATH of sultam precursors [71, 72], including examples where the supporting material has sulfonyl groups and therefore assists reactions in water [73]. The synthesis of an amphiphilic polystyrene-type immobilized TsDPEN ligand and its application in ATH of cyclic sulfonimines has been reported (Fig. 16) [74]. 

THE OLEFIN METATHESIS REACTIONS COMBINED WITH ORGANO-mON ARENE ACTIVATION TOWARDS DENDRIMERS AND POLYMERS... 

A review article examines the literature up to 1999 on silicon- and amine-based ferrocene dendrimers and polymers and those immobilized on electrodes. In these dendrimers the ferrocene itself may be at the cote, the periphery, or be used as a spacer molecule. Some examples of these molecules are shown as 15-17. ... 

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