Thiolate‐Protected Metal Nanoclusters: Recent Development in Synthesis, Understanding of Reaction, and Application in Energy and Environmental Field

Abstract

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.

To inorganic nanoparticles via nanoclusters: Nonclassical nucleation and growth pathway

“…Recent studies show that several numbers of discrete Au atoms are observed during the synthesis of Au NPs, indicating that crystal growth via the nonclassical nucleation model is a universal concept 26,34–36,96–100 . Kinetic control on the growth by controlling precursor‐to‐ligand ratio shows Au nanoclusters or complexes are metastable intermediates between the precursor and NPs in the synthesis of Au NPs 35 .…”

“…Various nanoclusters have found many potential applications derived from their unique physiochemical properties such as PL, catalytic activity, and magnetism. PL of nanoclusters is one of the most intriguing properties for applications, because it can be easily tuned and enhanced with various strategies, such as tailoring their size, structure, composition, state‐of‐aggregation, and self‐assembly 99,136–139 . When compared with representative fluorophores, nanoclusters are beneficial in terms of their photostability and biocompatibility, inspiring applications in chemical sensing, bioimaging, optoelectronics, phototherapy, and drug delivery 5 …”

Heterometallic Ni–Pt Chini-Type Carbonyl Clusters: An Example of Molecular Random Alloy Clusters

“…Random alloy clusters represent an alternative to site-specific doping and metal segregation that can be observed when different metals are mixed in the molecular and nanoscale domain. 14 − 23 , 29 − 31 …”

Toward the creation of high-performance heterogeneous catalysts by controlled ligand desorption from atomically precise metal nanoclusters

“…For the synthesis and electronic/geometrical structure of these metal NCs, we point the interested reader to a number of reviews published in the last few years by several groups, including ours. 23,24,[85][86][87][88][89][90][91][92][93][94][95] Regarding these atomically precise metal NCs, in 2010, Jin et al found that Au 25 (PET) 18 (PET = phenylethanethiolate) can function as either a homogeneous catalyst (sometimes called quasi-homogeneous; Fig. 1A) or a heterogeneous catalyst (Fig.…”