期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 16, 期 15, 页码 4650-4658出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.200902654
关键词
metathesis; monoliths; nanoparticles; ring-opening polymerization; supported catalysts
资金
- Deutsche Forschungsgemeinschaft (DFG) [BU 2174/1-1, BU 2174/1-2]
- Free State of Saxony
- Federal Ministry of Education and Research
Monolithic polymeric supports have been prepared by electron-beam-triggered free-radical polymerization using a mixture of glycidyl methacrylate and trimethylolpropane triacrylate in 2-propanol, 1-dodecanol, and toluene. Under appropriate conditions, phase separation occurred, which resulted in the formation of a porous monolithic matrix that was characterized by large (convective) pores in the 30 pm range as well as pores of <600 nm. The epoxy groups in pores of >7 nm were hydrolyzed by using poly(styrenesulfonic acid) (M-w = 69400 gmol(-1), PDI=2.4). The remaining epoxy groups inside pores of <7 nm were subjected to aminolysis with norborn-5-en-2-ylmethylamine (2) and provided covalently bound norborn-2-ene (NBE) groups inside these pores. These NBE groups were then treated with the first-generation Grubbs initiator [RuCl2(PCy3)(2)(CHPh)]. These immobilized Ru-alkylidenes were further used for the surface modification of the small pores by a grafting approach. A series of monomers, that is, 7-oxanorborn-5-ene-2,3-dicarboxylic anhydride (3), norborn-5-ene-2,3-dicarboxylic anhydride (4), N,N-di-2-pyridyl-7-oxanorborn-5-ene-2-carboxylic amide (5), N,N-di-2-pyridyl-norborn-5-ene-2-carboxamide (6), N-[2-(dimethylamino)ethyl]bicyclo[2.2.1]hept-5-ene-2-carboxamide (7), and dimethyl bicyclo[2.2.1]hept-5-en-2-ylphosphonate (8), were used for this purpose. Finally, monoliths functionalized with poly-5 graft polymers were used to permanently immobilize Pd2+ and Pt4+, respectively, inside the pores. After reduction, metal nanoparticles 2 nm in diameter were formed. The palladium-nanoparticle-loaded monoliths were used in both Heck- and Suzuki-type coupling reactions achieving turnover numbers of up to 167000 and 63000, respectively.
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