New Protocols for the Synthesis of Stable Ag and Au Nanocluster Molecules

Catching metals in the nonmetallic form in solution, as they grow to bulk, is one of the most exciting areas of contemporary materials research. A new kind of stabilization to catch the nonmetallic form of noble metals with small thiols has evolved as an exciting area of synthesis during the past decade. Gold clusters stay in the frontline of this research, yielding new molecules composed of a few to several hundreds of atoms. By taking guidelines from gold cluster research, various new protocols for silver nanoclusters were developed. In this Perspective, we highlight the recent advances on the synthesis of atomically precise silver, gold, and their alloy dusters with a special emphasis on silver. As a result of intense efforts of the recent past, clusters such as Ag-7,Ag-8(SR)(7,8), Ag-7(-S-R-S-)(4), Ag-9(SR)(7), Ag-32(SR)(19), Ag-44(SR)(30), Ag-140(SR)(53), Ag-280(SR)(140), and Ag-152(SR)(60) (SR and S-R-S refer to thiolate and dithiolate ligands, respectively) were added to the literature. Moreover, silver-covered and gold-covered alloy dusters have also been synthesized. Early reports of the crystallization of such dusters are available. Several of these dusters are shown to act as sensors, catalysts, and pesticide degradation agents, which suggests that these materials may find applications in daily life in the foreseeable future.