Molecular Additives as Competitive Binding Agents to Control Supramolecular-Driven Nanoparticle Assembly

Colloidal nanoparticle assembly methods can produce intricate superlattice structures and often use knowledge of atomic crystallization behaviors to guide their design. While this analogy has enabled multiple routes to programming colloidal crystallization thermodynamics, fewer tools or strategies exist to manipulate nanoparticle superlattice growth kinetics in a controlled manner. Here we investigate how small-molecule additives can be used to modulate the thermodynamics and kinetics of supramolecular-chemistry-driven nanoparticle assembly. Specifically, we introduce monovalent binding agents into the superlattice growth solution that compete with the multivalent interparticle bonding interactions driving particle assembly, thereby altering interparticle bond strength by reducing the number of bridging complexes formed between particles. In this manner, the assemblies can be steered to avoid kinetic traps and crystallize into faceted single crystals under isothermal conditions, alleviating the need for precise thermal control that has conventionally been required to produce large, faceted crystals in prior assembly methods.