Colloidal Synthesis of Plasmonic Complex Metal Nanoparticles: Sequential Execution of Multiple Chemical Toolkits Increases Morphological Complexity

In nature, complexity emerges systematically, progressing from atoms to molecules, cells, and, ultimately, complex living organisms. This natural bottom-up evolution inspired chemists to devise similarly organized processes for the creation of complex artificial matter. Similarly, the systematic design of customizable, complex nanocrystals has long been a fundamental goal. In this review, we present a comprehensive collection of chemical toolkits consisting of versatile, on-demand steps for the sequential synthesis of morphologically complex plasmonic nanoparticles (NPs). By integrating multistep synthetic routes, we introduce a list of chemical toolkits that enable combinable synthetic steps. This approach facilitates the controlled, multistep synthesis of shape-complex plasmonic NPs. We demonstrate how these designable chemical toolkits, when applied sequentially or in tailored combinations, enable the rational design of advanced plasmonic nanostructures with unprecedented complexity and structural hierarchy. This ultimately opens the door to an extensive, systematically expandable library of nanostructures with tailored functionalities. Through the advancement of this rationally designed synthetic approach, we aim to establish a "multiple stepwise synthesis" framework for fabricating shape-complex plasmonic building blocks, thus providing a roadmap for designing the next generation of plasmonic NPs.