Patterned Transparent Conductive Au Films through Direct Reduction of Gold Thiocyanate

Construction of structurally defined, patterned metal films is a fundamental objective in the emerging and active field of bottom-up nanotechnology. A new strategy for constructing macroscopically organized Au nanostructured films is presented. The approach is based upon a novel phenomenon in which incubation of water-soluble Au(SCN)(4)(1-) complex with amine-displaying surfaces gives rise to spontaneous crystallization and concurrent reduction, resulting in the formation of patterned metallic gold films. The Au films exhibit unique nanoribbon morphology, likely corresponding to aurophilic interactions between the complex moieties anchored to the amine groups through electrostatic attraction. Critically, no external reducing agents are needed to initiate or promote formation of the metallic Au films. In essence, the thiocyanate ligands provide the means for surface targeting of the complex, guide the Au crystallization process and, importantly, donate the reducing electrons. It is shown that the Au films exhibit electrical conductivity and high transparency over a wide spectral range, lending the new approach to possible applications in optoelectronics, catalysis, and sensing. In a broader context, a new gold chemistry route is presented in which ligand-enabled crystallization/reduction could open the way to a wealth of innovative reaction pathways and applications.