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    Generation of size-controlled Pd0 nanoclusters inside of the nanoporous domains of gel-type resins: diverse and convergent support to a strategy of "Template Controlled Synthesis"

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    In the realm of supported metal catalysis, the metal component is usually present as nanoparticles dispersed on the surface of suitable metal oxides or on active carbon. Synthetic procedures are normally directed to the generation of size-controlled metal nanoclusters, whose circumstances become mandatory when reactions to be catalyzed are “structure sensitive”.In general, size control has been achieved by: directly manufacturing metal-oxide-supported catalysts;by the generation of kinetically stabilized metal nanoclusters in the liquid phase and subsequent transfer of the protected nanoclusters on to suitable supports; by generating metal nanoclusters inside isoporous inorganic materials such as mesoporous silicas. Herein, we report on three independent, convergent pieces of structural evidence of this template-controlled synthesis strategy to obtain size-controlled metal nanoclusters suitable for synthesizing resin-supported metal catalysts

    Polybenzimidazole as a Promising Support for Metal Catalysis: Morphology and Molecular Accessibility in the Dry and Swollen State

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    Polybenzimidazole (PBI) in beaded form (250-500 mu m) has been characterized in the dry state by scanning electron microscopy (SEM), BET, and nitrogen porosimetry. In the swollen state, it has been characterized by inverse steric exclusion chromatography (ISEC) in tetrahydrofuran, toluene, and water, by ESR of TEMPONE (2,2,6,6-tetramethyl-4-oxo-1-oxypiperidine). and pulse field gradient spin echo (PGSE) NMR spectroscopy, toluene, in tetrahydrofuran, ethanol and water. The dry-state results are in good agreement with the ISEC results obtained in tetrahydrofuran, toluene, and water with regard to the 40-80 nm macroporosity. The swelling-dependent surface area and pore volume detected by ISEC in toluene and water reveal the amphiphilic nature of PBI
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