Nanoscale Spatial Separation to Regulate Gold Microstructures Formation

Flower-like gold microstructures are directly formed from solution on the surface of nanometric molecular assemblies. We show that the size and morphology of these microstructures are controlled by the nanoscale thickness of the assemblies, which consist of ruthenium polypyridyl complexes crosslinked with a palladium salt. Gold electrodeposition on these ultrathin (3-15 nm) molecular assemblies, bound to a conductive substrate, follows an instantaneous nucleation regime that results in multiple small clusters. On thicker assemblies (15-55 nm) a progressive nucleation mode is dominant, which leads to the formation of larger (up to 50 times) and highly branched microstructures. The ability to control the characteristics of these microstructures by nanoscale assemblies is based on the mechanistic insights of the nucleation and growth processes obtained by electrochemical means and scanning electron microscopy (SEM) measurement.