Harnessing Dynamic Heteroleptic Complexation for Self-Assembly of Robust Nested Metallo-Supramolecular Cages.

The exclusive formation of artificial multicomponent assemblies remains a significant challenge, in contrast to the well-established organization observed in natural systems, due to intrinsic entropic constraints. To overcome this limitation, recent efforts have been focused on developing precision self-assembly strategies for the rational construction of such architectures. Here, we construct an ideal complementary pair of 2,2':6',2″-terpyridine (tpy)-based ligands by fine-tuning the substituent bulkiness, which enables the quantitative formation of robust nested cages through efficient dynamic heteroleptic complexation with multivalent coordination. The multivalent ligand design proves essential for successful self-assembly, as the smaller incarcerated cage cannot be independently synthesized in an exclusive manner. Notably, the improved solubility and exceptional stability of the nested cage even at low concentrations allow for structural characterization by high-field nuclear magnetic resonance (NMR) spectroscopy, solution-based small-angle X-ray scattering (SAXS), and scanning transmission electron microscopy (STEM). Moreover, its well-defined internal cavity permits the in situ reductive formation of gold nanoparticles, demonstrating its potential as a functional nanoreactor.