Nanodusters

Chui, Y.H., Grodiola, G., Snook, l.K. and Russo, S.P. (2007) Molecular dynamics investigation of the structural and thermodynamic properties of gold nanodusters of different morphologies. Physical Review B - Condensed Matter, 75, 033404-1-033404-4. 

Xing, X., Yoon, B., Landman, U. and Parks, J.H. (2006) Structural evolution of Au nanodusters From planar to cage to tubular motifs. Physical Review B Condensed Matter, 74,165423-1—165423-6. 

Magyar, R.J., Mujica, V., Marquez, M. and Gonzalez, C. (2007) Density-functional study of magnetism in bare Au nanodusters Evidence of permanent size-dependent spin polarization without geometry relaxation. Physical Review B -Condensed Matter, 75,144421-1—144421-7. 

We demonstrated that the morphology of nanostructures, electrochemical, and photoelectrochemical properties in the electrodes modified with nanodusters of Qo can be controlled by applying a strong magnetic field. The present study provides useful information for designing novel nanodevices whose photofunctions can be controlled by a magnetic field. 

Metal Nanodusters Synthesis and Strategies for their Size Control... 

Metal Nanodusters Electronic Aspects and Physico-Chemical Characterization... 

Platinum Nanodusters Size and Surface Structure Sensitivity... 

Metal Nanodusters Supported on Cross-Linked Functional Polymers... 

Synthesis of Metal Nanodusters upon Using Ion Implantation... 

Template Synthesis and Catalysis of Metal Nanodusters in Ordered Mesoporous Silicas... 

The alternation of temperature in a hydrothermal reaction was demonstrated to be crucial in changing the crystal phases or morphologies of nanomaterials. In the case of K2Cr207, when the reaction temperature was increased to 180 °C, K-OMS-2 microspheres consisting of nanoneedles were synthesized in contrast to the nanoduster arrays composed of tetragonal prism nanorods synthesized at 120 °C (Figure 8.1a-c). In the case of Na2Cr207, when the reaction temperature was 100 °C, Na-OMS-2 phase was formed. However, when the reaction temperature was... 

Two crucial factors required for the successful development of these applications are the need to synthesize the appropriate nanoduster molecules in such a manner as to have zero size distribution and to be able to structurally characterize the products obtained. The numerous practical applications of binary late-metal chalco-genide semiconductors [1] have spurred the development of chemical methods to access nanometer-sized pieces of these solid materials, where single crystal diffraction can be used to eluddate the three-dimensional structure of the clusters obtained. 

P. V. Kamat D. Meisel, eds. Semiconductor Nanodusters-Physical, Chemical and Catalytic Aspects. Studies in Surface Science and Catalysis. Elsevier Science Amsterdam. 474 1997. 

F. Pittner T. Schalkhammer, A self assembled shell of 11-mercaptounde-canoic aminophenylboronic acids on gold nanodusters. Mat. Sci. Eng C — Biomimedc and Supramol. Syst. 1999,... 

In another example, nanodustered Pt(0) catalysts based on cross-linked macro-molecular matrixes were evaluated in the hydrogenation of an a,(i-unsaturated aldehyde, citral. The monometallic catalysts exhibit remarkable selectivity for gera-niol/nerol when 2-3 nm, regularly shaped, spherical metal nanoclusters are deposited on the supports from solutions of solvated platinum atoms prepared by metal vapor synthesis (MVS). The immobilization in the polymer framework of ions of a second metal such as Fe(II), Co(II), or Zn(II) enhances the selectivity of the Pt catalysts by up to more than 90% [18],... 

Volume 103 Semiconductor Nanodusters - Physical, Chemical, and Catalytic Aspects edited by RV. Kamat and D. Meisel... 

This mechanism is equivalent to the two-step mechanism for transition-metal nanocluster self-assembly, from metal salts under reductive conditions, proposed by Finke [81, 83] with one main conceptual difference, in the case of Pt, since Pt2(dba)3 is a Pt(0) nanoduster precursor in the zero oxidation state, the first step (a) in Scheme 6.3, must be considered to be the organometaUic complex decomposition, and not a metal nudeation step as occurs, for example, when using a Pt precursor in an oxidation state different to zero. 

The hydrogenation kinetics of cydohexene catalyzed by Pt2(dba)3 dispersed in BMI.PFg, BMI.BF4 and BMl,OTf are shown in Fig. 6.3. The kinetics curves were treated using the pseudo-elementary step and fitted (Eq. (6.1) by the following integrated rate equation for metal-salt decomposition (A —> B, hi) and autocatalytic nanoduster surface growth (A + B — 2B, 2). For a more detailed description of the use of the pseudo-elementary step for the treatment of hydrogenation kinetic data and derivation of the kinetic equations see elsewhere [81-83]. 

As expected, the kinetic curve of Fig. 6.3 shows no induction period, indicating that the first step, the Pt2(dba)3 decomposition, is fast and the catalyst nanoduster B is readily available from the onset of the hydrogenation reaction. The rate constants values obtained from the fit of Fig. 6.3 are summarized in Table 6.2. 

Rothenberg and coworkers studied the application of mixed-metal nanodusters in the Suzuki reaction. They made small tetra-octylammonium formate stabilised clusters (1.6-2.1 nm) based on Cu, Ru, Pd and Pt and binary and ternary combinations thereof Of the single metals, Pd was the most active, but surprisingly, Cu and Ru also showed good activity. The mixed Cu—Pd nanocluster was as active as the Pd nanodusters [44]. 

Rhee et al. have described the synthesis of bimetaUic Pd-Rh nanoparticles within dendrimers as nanoreactors [56]. The resulting nanodusters effidently promoted the partial hydrogenation of l,3mild conditions with promising catalytic activity (Scheme 11.3). The dendrimer-encapsulated Pd-Rh bimetalUc nanocatalysts could be reused without significant loss of catalytic activity. 

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