Rare Earth Oxide Superstructures Assembled via Surface Ligand Switching at High Temperature

Superstructures comprised of precisely controlled building blocks open opportunites in the rational design and manufacture of functional materials. However, there is a scarcity of synthetic techniques to facilitate the mass production of these materials. Here we present a scalable synthesis of superstructures assembled from atomically precise Ce₂₄O₂₈(OH)₈ and generalize the method to other rare-earth oxide nanoclusters. Combining operando small-angle X-ray scattering, <i>ex-situ</i> molecular and structural characterizations and molecular dynamics simulations, we provide a detailed description of the self-assembly mechanism. At high temperature, oleate ligands on the nanoclusters are replaced by benzoate supplied from chemical decomposition of the solvent. This benzoate, participating in pi-pi stacking interactions, drives the self assembly of the superstructures. Removing the benzoate with oleate again at room temperature controls superstructure disassembly into principle component nanoclusters that can be used for the synthesis of multicomponent superstructures, demonstrated up to 5 rare earth element componenets. The implementation of this synthetic approach, combined with an understanding of the mechanisms involved, offers exciting prospects for generating superstructures that are well-suited for materials applicable to electronics, plasmonics, magnetics, and catalysis.