Dynamic and asymmetric colloidal molecules.

"Colloidal molecules" represent artificial colloidal clusters replicating the geometries of molecules and exhibiting flexibility and fluctuations similar to macromolecules and proteins. Their dynamic and anisotropic characters make them unique and indispensable building blocks for creating hierarchically organized superstructures. Despite the progress in synthesizing and assembling colloidal molecules, unveiling their dynamic characters is challenging in experiments. Here, we employ real-time three-dimensional imaging and simulations to reveal dynamic colloidal molecule structures in micrometre-sized colloidal-emulsion models with tunable electrostatic interactions. Our findings reveal that colloidal molecules' dynamic structures are inherently asymmetric, with angular symmetry emerging through continuous ordering from a liquid-like configuration. We further develop an effective method to guide the ordering of colloidal molecules towards a desired structure by dynamically adjusting the ionic strength in the solvent during the ordering process. We validate this method using molecular dynamics simulations and propose a practical protocol for its experimental implementation. Our research contributes to a clearer physical understanding of dynamic colloidal molecules and offers potential solutions to the complexities inherent in their formation process.