Microgel-stabilised gold nanoclusters: powerful "quasi-homogeneous" catalysts for the aerobic oxidation of alcohols in water

Gold nanoclusters of small size (2.5 nm) and narrow size distribution were synthesized in solution using tailor-made soluble cross-linked polymers (microgels) as exotemplates and stabilizers. The resulting microgel-stabilized nanoclusters could be conveniently isolated by precipitation, stored in the solid state, and redispersed in water and polar organic solvents. They were found to exhibit remarkable catalytic activity (average TOF up to 960 h(-1)) in the aerobic oxidation of benzylic and aliphatic alcohols and also of polyols in water under mild conditions (50-70 degrees C, 1-3 atm O2).