Formation of spherical nanostructures by the controlled aggregation of gold colloids

Stable suspensions of size-uniform spherical assemblies of 5-8 nm gold colloids in toluene are readily obtained by cross linking the colloidal particles using alkanedithiols within a defined range of gold-dithiol molar ratios. The assemblies are very stable and remain suspended in toluene for several months without significant aggregation. These porous gold spheres can be further organized into hierarchically assembled relatively linear chains by the addition of ethanol.