Thermally responsive gold nanocatalysts based on a modified poly-vinylpyrrolidone
Poly-vinylpyrrolidone (PVP) stabilized nanoparticle (NP) catalysts are among the most active NP catalysts demonstrating excellent activities and stabilities in a wide and diverse range of reactions. One of the main limitations, that tend to prevent their use in industrial processes, is that they cannot be easily separated from reactions that are not amenable to biphasic separations, i.e. those involving hydrophilic reaction products. We describe a durable and recyclable Au NP catalyst system based on modified PVP that is thermo-sensitive, termed C-1-PVP. C-1-PVP stabilized Au NPs are similar in size, and exhibit similar properties, to Au NPs stabilized by PVP, but their additional thermo-sensitivity enables their facile separation from hydrophilic reaction products by mild heating, resulting in their precipitation. XRD, XPS, TEM, temperature dependant NMR, DLS and UV-vis analysis, as well as catalytic recycling and metal leaching tests were carried out to fully characterize the thermo-sensitive behavior of C-1-PVP stabilized Au NPs. The C-1-PVP stabilized Au NPs were systematically compared to Au NPs stabilized by PVP demonstrating the superiority of the new system and their potential green benefits. (C) 2013 Elsevier B.V. All rights reserved.