Construction of structurally defi ned, patterned metal fi lms is a fundamental objective in the emerging and active fi eld of bottom-up nanotechnology. A new strategy for constructing macroscopically organized Au nanostructured fi lms 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 fi lms. The Au fi lms 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 fi lms. 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 fi lms 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 ligandenabled crystallization/reduction could open the way to a wealth of innovative reaction pathways and applications.

Extremely long gold nanowires spontaneously assemble in a water-dimethylsulfoxide (DMSO) solution of Au(SCN)4(-). The Au nanowires were crystalline, exhibited a very high aspect ratio, and, importantly, were produced without co-addition of reducing agents. Transparent conductive films were formed by surface deposition of the nanowires and plasma treatment.

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been applied for creating microscale surface organization.[ 8 ] Related metal patterning technologies based upon evaporationinduced self-alignment, [9][10][11] direct laser sintering, [12][13][14] and micro-(or nano-) transfer molding have been also reported. [15][16][17][18][19][20][21] However, these techniques also generally require that metallic nanostructures (i.e., nanorods, nanowires, etc.) are prepared prior to surface deposition and patterning. Methodologies combining top-down and bottom-up approaches have been also introduced. [ 22 ] We present a novel, versatile "chemical lithography" strategy for fabricating largearea, organized conductive gold micropatterns. The technology employs a simple single-step process in which a gold complex undergoes slow crystallization/reduction in a confi ned environment. Specifi cally, we demonstrate that diverse patterns of well-defi ned, uniform Au microwires are spontaneously formed through incubation of gold thiocyanate [Au(SCN) 4 − ] dissolved in an organic-solvent/water mixture within confi ned spaces at the interface between polymer molds and surfaces underneath them. The patterning technology is generic in nature as Au organization is only determined by the mold employed. Importantly, the entire patterning process-Au reduction and crystallization, control of microwire size, shape, and organization-occurs spontaneously without any nanostructure pre-synthesis steps. Furthermore, neither stabilizing or shape-directing ligands, nor reducing agents are required for assembly of the Au patterns, as the reducing electrons originate from the thiocyanate ligands. The Au microwires are electrically conductive and produce optically transparent surfaces, pointing for practical uses of the technology as a platform for creation of diverse optoelectronic assemblies and devices. Results and DiscussionThe experimental scheme is illustrated in Figure 1 . An organicsolvent/water solution containing KAu(SCN) 4 is spread upon a solid substrate (Figure 1 A). A polydimethylsiloxane (PDMS) mold having pre-designed pattern is then placed upon the fi lm, effectively confi ning the Au(SCN) 4 − solution into the spaces determined by the stamp (Figure 1 B). Incubation of the gold complex solution within the confi ned areas prevents rapid evaporation of the solvent mixture, instead resulting in slow deposition of Au microwires following crystallization and reduction of the Au 3+ ions by the thiocyanate residues. Recent studies have shown that

Bottom-up synthesis offers novel routes to obtain nanostructures for nanotechnology applications. Most self-assembly processes are carried out in three dimensions (i.e. solutions); however, the large majority of nanostructure-based devices function in two dimensions (i.e. on surfaces). Accordingly, an essential and often cumbersome step in bottom-up applications involves harvesting and transferring the synthesized nanostructures from the solution onto target surfaces. We demonstrate a simple strategy for the synthesis and chemical transformation of tellurium nanorods, which is carried out directly at the solid-solution interface. The technique involves binding the nanorod precursors onto amine-functionalized surfaces, followed by in situ crystallization/oxidation. We show that the surface-anchored tellurium nanorods can be further transformed in situ into Ag2Te, Cu2Te, and SERS-active Au-Te nanorods. This new approach offers a way to construct functional nanostructures directly on surfaces.