Au38S2(SAdm)20 Photocatalyst for One-Step Selective Aerobic Oxidations

We here report a protocol for the synthesis of Au38S2(SAdm)(20) nanoclusters (-SAdm = 1-adamantanethiolate) with a higher production yield (10%) in comparison to previous reported methods. The photosensitizing properties of the gold nanoclusters are investigated for the formations of singlet oxygen (O-1(2)) using visible light wavelengths of 532 and 650 nm. The formation of O-1(2) was detected by 1,3-diphenylisobenzofuran as the chemical trapping probe as well as direct observation of the characteristic O-1(2) emission (ca. 1276 nm). The efficiency of the O-1(2) formation using the Au38S2(SAdm)(20) nanoclusters is found to be notably higher than that of Au-25(SR)(18) nanoclusters. Finally, selective aerobic oxidations of sulfide to sulfoxide and benzylamine to imine in the presence of oxygen (O-3(2)) and photoexcited Au38S2(SAdm)(20) are well studied. This work demonstrates the promise of Au38S2(SAdm)(20) nanoclusters in the generation of activated singlet oxygen for selective catalytic reactions.