Self-Organization of Gold Nanoparticles Coated with a Monolayer of Azobenzene Liquid Crystals

A gold nanoparticle having a monolayer of azobenzene liquid crystal (LC) was synthesized. The size of the gold nanoparticle obtained was 4.7 nm in average diameter, and it was soluble in common non-polar organic solvents such as toluene and dichloromethane. We confirmed that the reversible photochemical and thermal isomerization of the azobenzene could take place on the surface of the gold nanoparticles in analogy with free azobenzenes in solutions. Furthermore, a 1-dimensional self-organization of the nanoparticle was observed by transmission electron microscopy. However, a gold nanoparticle without LC molecules never showed such self-organization. Therefore, we conclude that the self-organization of the gold nanoparticle is based on the liquid crystallinity of the organic ligands attached on their surface.