Dendrimer derivative

Two fractions of atactic polystyrene dendrimer derived from monomer 12(G-2) were investigated by GPC and LS under conditions where no aggregation occurs. Whereas GPC gave Mw=82,000 and Mw= 600,000, LS furnished... 

Fig. 2. Schematic representation of the supramolecular cylinders of the dendrimer derived from macromonomer 9 (R=OC12H25,n=3) in the Qh mesophase atop view of a cylinder containing six repeat units in a stratum with the alkyl tails melted to match the average column radius determined by X-ray scattering experiments b side view of a cylinder containing 30 repeat units of the polymer assembled with melted alkyl tails. Reproduced with permission from references 5 a...

Fig. 3. An idealized representation of the supramolecular cylinder self-assembled from a single chain of the dendrimer derived from monomer 9 (R=OC12H25, n=3) in the hexagonal columnar phase, assuming one single backbone per cylinder, drawn to proportion with existing experimental data a tilted side view b top view. Reproduced with permission from references 5 a...

After cooling to room temperature, the sugar-dendrimer derivative may be precipitated with a large volume of methanol. The precipitate may be purified from reaction products by dialysis against water or buffer using a membrane with a molecular weight cutoff of 3500 Daltons. The final product may be stored frozen or lyophilized to a white powder. 

Using the dendrimer route, it is possible to prepare supported catalysts not available via traditional routes. Dendrimer derived Pt-Au catalysts having compositions within the bulk miscibility gap can be prepared on several oxide supports. For all the supports studied, the bimetallic catalysts exhibited synergism with respect to mono- and cometallic catalysts for the CO oxidation and hydrocarbon NOx SCR reactions. The bimetallic Pt-Au catalysts also showed evidence of exchanging surface and subsurface atoms in response to strongly binding ligands such as CO. 

G. Lafaye, C. T. Williams, and M. D. Amiridis, Synthesis and microscopic characterization of dendrimer-derived Ru/A1203 catalysts, Catal. Lett. 96, 43-47 (2004). 

Information about transmission of chirality in dendrimer molecules also came from various generations of dendrimers derived from optically active alkaloids. Starting from atropine or quinine, corresponding ammonium salts 1 or 2, respectively, of up to the third generation were synthesised by quatemisation at the aliphatic nitrogen with Frechet-type dendritic benzyl bromides (Fig. 4.67) [22]. 

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