Size Focusing: A Methodology for Synthesizing Atomically Precise Gold Nanoclusters

Controlling nanoparticles with atomic precision, somewhat like the way organic chemists control small molecules by organic chemistry principles, is highly desirable for nanoparticle chemists. Recent advances in the synthesis of gold nanoparticles have opened the possibility to precisely control the number of gold atoms in a particle. In this Perspective, we will discuss a size-focusing methodology that has been developed in the synthesis of a number of atomically monodisperse ultrasmall gold nanoparticles (also called nanoclusters). We focus our discussion on thiolate-stabilized Au nanoclusters (referred to as Au n (SR) m, where n and m are the respective number of metal atoms and ligands). The underlying principle of this size-focusing process is primarily related to the peculiar stability of certain sized Au n (SR) m nanoparticle, that is, “survival of the robustest”, much like the natural law “survival of the fittest”. We expect that this universal size-focusing method will ultimately allow for preparing a full series of size-discrete, atomically monodisperse nanoparticles that span the size regimes of both nonplasmonic nanoclusters and plasmonic nanocrystals. These well-defined nanoparticles will be of major importance for both fundamental science research and technological applications.