The Lanthanide Contraction beyond Coordination Chemistry

The lanthanide contraction is conceptualized traditionally through coordination chemistry. Here we break this mold in a structural study of lanthanide ions dissolved in an amphiphilic liquid. The lanthanide contraction perturbs the weak interactions between molecular aggregates that drive mesoscale assembly and emergent behavior. The weak interactions correlate with lanthanide ion transport properties, suggesting new strategies for rare‐earth separation that exploit forces outside of the coordination sphere. Outside chances: The lanthanide contraction manifests outside of the coordination sphere, influencing mesoscale ordering and emergent material properties that impact important applications.