DFT calculations for aerobic oxidation of alcohols over neutral Au6cluster

Lately, it was found that the Au nanoclusters stabilised by poly(N-vinyl-2-pyrrolidone) [PVP; (C6H9ON)n], abbreviated to Au:PVP, can oxidise p-hydroxybenzyl alcohol selectively into the corresponding aldehyde in water without degradation. This observation indicates that Au cluster can exhibit high catalytic activity without any metal oxide supports. From previous works, it was found that the anionic Au clusters played an important role for the activation of oxygen molecule on the Au clusters. However, the catalytic activity of neutral Au clusters for the aerobic oxidation reaction of alcohol is not still investigated in detail. In order to examine the catalytic activity of neutral Au clusters, the aerobic oxidation of p-hydroxybenzyl alcohol to the corresponding aldehyde catalysed by Au6 has been investigated quantum chemically using density functional theory with the PBE0 functional. Possible reaction pathways are investigated taking account of full structure relaxation of the model systems. From the calculation results, it was found that the formations of both a hydroperoxyl anion and a hydride were the important steps for the aerobic oxidation of p-hydroxybenzyl alcohol over Au6 cluster.