Metal nanoclusters (NCs), which are composed of about 250 or fewer metal atoms, possess great potential as novel functional materials. Fundamental research on metal NCs gradually started in the 1960s, and since 2000, thiolate (SR)‐protected metal NCs have been the main metal NCs actively studied. The precise and systematic isolation of SR‐protected metal NCs has been achieved in 2005. Since then, research on SR‐protected metal NCs for both basic science and practical application has rapidly expanded. This review describes this recent progress in the field of SR‐protected metal NCs in three areas: synthesis, understanding, and application. Specifically, the recent study of alloy NCs and connected structures composed of NCs is highlighted in the “synthesis” section, recent knowledge on the reactivity of NCs in solution is highlighted in the “understanding” section, and the applications of NCs in the energy and environmental field are highlighted in the “application” section. This review provides insight on the current state of research on SR‐protected metal NCs and discusses the challenges to be overcome for further development in this field as well as the possibilities that these materials can contribute to solving the problems facing modern society.

Metal nanoclusters (NCs), which consist of several, to about one hundred, metal atoms, have attracted much attention as functional nanomaterials for use in nanotechnology. Because of their fine particle size, metal NCs exhibit physical/chemical properties and functions different from those of the corresponding bulk metal. In recent years, many techniques to precisely synthesize metal NCs have been developed. However, to apply these metal NCs in devices and as next-generation materials, it is necessary to assemble metal NCs to a size that is easy to handle. Recently, multiple techniques have been developed to form one-, two-, and three-dimensional connected structures (CSs) of metal NCs through self-assembly. Further progress of these techniques will promote the development of nanomaterials that take advantage of the characteristics of metal NCs. This review summarizes previous research on the CSs of metal NCs. We hope that this review will allow readers to obtain a general understanding of the formation and functions of CSs and that the obtained knowledge will help to establish clear design guidelines for fabricating new CSs with desired functions in the future.

This review summarizes previous studies on high-resolution separation of Aun(SR)m clusters for better understanding the utility of each separation technique.

To use atomically precise metal nanoclusters (NCs) in various application fields, it is essential to establish size-selective synthesis methods for the metal NCs. Previous studies on thiolate (SR)-protected gold NCs...

Kornberg 4-4-Mercaptobenzoic Acid, p-MBA 102 Au 102 (p-MBA) 44 X 21 HPLC Au n (SR) m Au n-x M x (SR) m 3 1