Single-Atom Migration into a Chiral Multilayer Nanocluster Architecture

Colloidal nanocrystals are generally regarded as rigid solid entities, rarely exhibiting the structural adaptability observed in molecular cages, such as fullerenes, which can undergo carbon framework reduction and encapsulate guest cations without structural reorganization. Here, by creating two enantiomeric pairs of high-nuclearity copper sulfide nanoclusters with a mixed-valence Cu(II)/Cu(I) configuration, we endow these nanoscale assemblies with an intrinsic capacity for electron uptake under mild reducing conditions. The resulting charge imbalance provides an effective thermodynamic driving force that realizes a positively charged metal ion migrating inward through multiple atomic layers and occupying the cluster core. This system thus represents a rare example of a nanocluster platform that simultaneously combines reduction tolerance and structural robustness, preserving its atomic framework despite the incorporation of a single atom effectively modifying the electronic structure, particularly the local chirality. In situ absorption and circular dichroism spectroscopies establish that the transformation proceeds through a continuous, single-particle process rather than a fragmentation-reconstruction pathway, while ex situ pair distribution function analysis resolves key local steps in the structural evolution, offering mechanistic insights into this unique migration behavior.