Preparation and Characterization of Dendrimer-Encapsulated CdS Semiconductor Quantum Dots

Dendrimer-Encapsulated Metal Nanoparticles: Synthesis, Characterization, and Applications to Catalysis

“…6 In this approach, dendrimer-encapsulated Cu nanoclusters are prepared as described earlier, 3 and then upon exposure to Ag + the Cu particles oxidize to Cu 2+ ions and Ag + is reduced to yield a dendrimer-encapsulated zerovalent Ag nanoparticle (Scheme 3 and eq 1). Figure 5 shows the spectroscopic evolution of an intradendrimer displacement reaction between G6-OH-(Cu 55 ) and Ag + . Spectrum 1 is the UV-vis spectrum of G6-OH(Cu 55 ).…”

“…For example, dendrimer-encapsulated Pt/Pd nanoparticles are synthesized as follows. First, a solution containing G6-OH(Pt 55 ) is prepared by using the direct reduction approach already described. Next, PdCl 4 2-is added to this solution to form a mixed metal-ion intradendrimer composite: G6-OH-[(Pt 55 )+(Pd 2+ ) 55 ].…”

“…First, a solution containing G6-OH(Pt 55 ) is prepared by using the direct reduction approach already described. Next, PdCl 4 2-is added to this solution to form a mixed metal-ion intradendrimer composite: G6-OH-[(Pt 55 )+(Pd 2+ ) 55 ]. That is, Pd 2+ partitions into the dendrimer and complexes with tertiary amine sites vacated by Pt 2+ after the first reduction step.…”

“…The existence of the mixed-valent composite, which is nearly the sum of the two individual components, can be confirmed by UVvis spectroscopy. However, after reduction of G6-OH[(Pt 55 ) + (Pd 2+ ) 55 ], the intense LMCT band arising from Pd 2+ complexed to interior tertiary amines essentially disappears, and the interband transition due to the formation of the bimetallic nanoparticles appears. TEM also indicates a significant increase in particle size following the second reduction step.…”

“…53 More recently, Amis and co-workers, 35 Esumi et al, 36 and Goodson 54 have provided remarkably detailed microscopy, scattering, and photophysical data that have yielded additional insight into dendrimer encapsulation of metal nanoparticles. New results from our laboratory indicate that even semiconductor quantum dots (CdS) are accessible by this synthetic route, 55 and Amis et al have further expanded the scope of dendrimer-encapsulated nanoparticles by preparing them within monolithic dendrimer-containing polymer composites. 29,34 The approach described here for preparing dendrimerencapsulated nanoparticles takes advantage of the unique aspects of dendrimer structure: the chemistry of the terminal groups, the generation-dependent size, the threedimensional structure, the radial distribution function of polymer density, and the presence of endoreceptors within the dendrimer interior.…”