Colloidal Hybrid Nanoparticle Insertion Reaction for Transforming Heterodimers into Heterotrimers

Three-component colloidal hybrid nanoparticles, which are central to a diverse array of applications, are typically synthesized using successive seeded growth steps, which are additive in nature and driven by surface chemistry considerations and material-specific preferences for nucleation and growth. Here, we describe a new nanoparticle insertion reaction for transforming heterodimers into heterotrimers, which is based on a supersaturation-precipitation pathway that shifts the driving force for heterotrimer formation away from surface-driven nucleation and growth. To demonstrate the concept, a Ge segment is inserted between the Au and Fe₃O₄ domains of Au-Fe₃O₄ heterodimers to form Au-Ge-Fe₃O₄ heterotrimers. Microscopic investigations reveal important mechanistic insights, including identification of a proposed Au-Ge-Au-Fe₃O₄ intermediate. The process can be modified to access the analogous addition product Ge-Au-Fe₃O₄, allowing tuning between two distinct heterotrimer isomers with different configurations.