Formation of photoresponsive gold nanoparticle networks via click chemistry.

To tailor highly-functionalized gold nanoparticle (GNP) networks, we investigated the GNP network formation with functionalized spacer group via click chemistry. This is based on its high reactivity and mild reaction conditions. The feature of this protocol is the easy approach to versatile GNP functionalization on the basis of the excellent accessibility and good stability of functional dialkyne derivatives. We achieved the successful formation of GNP networks by reacting azide-appended GNPs and various dialkyne derivatives, supported by infrared absorption spectroscopy and transmission electron microscopy analyses. These GNP networks readily showed the unique physical properties similar to those of classical GNP networks prepared by ligand exchange reaction of bidentate functional spacers. Typically, the GNP network with the azobenzene unit as a functional spacer (GNP3) showed reversible photoinduced formation of three-dimensional aggregates followed by its isomerization in the network.