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The synthesis and characterization of nanoparticle-cored dendrimers (NCDs), consisting of a metal core capped by arylpolyethers terminated with ester or carboxylate groups, are reported. These NCDs, comprising nanometer-sized gold clusters at the core and organic dendrons radially connected to the gold core by gold-sulfur bonds, were analyzed by TEM, TGA, UV, IR, and NMR spectroscopies. The density of the branching units connected to the core decreased from 1.90/nm[SUP2] for a first-generation NCD (Au-G1 (CO[SUB2]Me)) to 0.80/nm[SUB2] for a fourth-generation NCD (Au-G4(CO[SUB2]Me)). Although the ester-terminated NCDs were stable and resisted aggregation, they were easily hydrolyzed to the corresponding watersoluble sodium salts. Aqueous solutions of (Au-Gn(CO[SUB2]Na)) exhibited micellar properties. Since these NCDs possess a relatively unpassivated metal core and an organic aryl ether shell with micellar and dendritic properties, they are expected to have important potential applications in catalysis. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of a group of new dendrimers—namely, nanoparticie-cored dendrimers (NCDs)—are described. These materials were obtained by the reduction of hydrogen tetrachloroaurate phase-transferred into toluene in the presence of Fréchet-type polyaryl ether dendritic disulfide wedges of generation 1-5. These materials, possessing nanometer-sized gold clusters at the core and dendritic wedges radially connected to the core by Au-S bonds, were analyzed by TEM and TGA, and by UV, IR, and NMR spectroscopies. The number of branching units connected to the core decreased with the generation of the dendritic wedge, and this number changed from 2.18/nm² for Au- G-2 to 0.27/nm² for Au-G-5. This result suggests that, in the higher-generation NCDs, a large fraction of the surface area of the metal cluster is not passivated and is therefore available for catalytic activity. [ABSTRACT FROM AUTHOR]