"Click" dendrimers: synthesis, redox sensing of Pd(OAc)2, and remarkable catalytic hydrogenation activity of precise Pd nanoparticles stabilized by 1,2,3-triazole-containing dendrimers.
"Click" dendrimers containing 1,2,3-triazolyl ligands that coordinate to PdII(OAc)2 have been synthesized in view of catalytic applications. Five of these dendrimers contain ferrocenyl termini directly attached to the triazole ligand in order to monitor the number of PdII that are introduced into the dendrimers by cyclic voltammetry. Reduction of the PdII-triazole dendrimers by using NaBH4 or methanol yields Pd nanoparticles (PdNPs) that are stabilized either by several dendrimers (G0, DSN) or by encapsulation inside a dendrimer (G1 and G2: DEN), as confirmed by TEM. Relative to PAMAM-DENs (PAMAM=poly(amidoamine)), the "click" DSNs and DENs show a remarkable efficiency and stability for olefin hydrogenation under ambient conditions of various substrates. The influence of the reductant of PdII bound to the dendrimers is dramatic, reduction with methanol leading to much higher catalytic activity than reduction with NaBH4. The most active NPs are shown to be those derived from dendrimer G1, and variation of its termini groups (ferrocenyl, alkyl, phenyl) allowed us to clearly delineate, optimize, and rationalize the role of the dendrimer frameworks on the catalytic efficiencies. Finally, hydrogenation of various substrates catalyzed by these PdNPs shows remarkable selectivity features.
Ornelas
Cátia
C
Nanosciences and Catalysis Group, Institut des Sciences Moléculaires, UMR CNRS No 5255, Université de Bordeaux I, 351 Cours de la Libération, 33405 Talence Cedex, France.
Aranzaes
Jaime Ruiz
JR
Salmon
Lionel
L
Astruc
Didier
D
D000085:Acetates / Q000737:chemistry*; D000475:Alkenes / Q000737:chemistry; D001393:Azoles / Q000737:chemistry*; D002384:Catalysis; D050091:Dendrimers / Q000138:chemical synthesis* / Q000737:chemistry*; D006865:Hydrogenation; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010984:Platinum / Q000737:chemistry*; D013053:Spectrophotometry; D017186:Titrimetry
D000085:Acetates; D000475:Alkenes; D001393:Azoles; D050091:Dendrimers; D008024:Ligands; D009942:Organometallic Compounds; C516071:palladium(II) acetate; D010984:Platinum