Regulation of lanthanide supramolecular nanoreactors via a bimetallic cluster cutting strategy to boost aza-Darzens reactions

Supramolecular nanoreactor as artificial mimetic enzyme is attracting a growing interest due to fine-tuned cavity and host-guest molecular recognition. Here, we design three 3d-4f metallo-supramolecular nanocages with different cavity sizes and active sites (Zn₂Er₄L¹₄, Zn₄Er₆L²₆, and Zn₂Er₈L³₈) based on a "bimetallic cluster cutting" strategy. Three nanocages exhibit a differential catalysis for the three-component aza-Darzens reaction without another additive, and only Zn₂Er₈L³₈ with the largest cavity and the most lanthanides centers has excellent catalytic conversion for monosubstituted and disubstituted N-aryl aziridine products. The host-guest relationship investigations confirm that Zn₂Er₈L³₈ significantly outperforms Zn₂Er₄L¹₄ with the smaller cavity and Zn₄Er₆L²₆ with the fewer Lewis acidic sites in multi-component reaction is mainly attributed to the synergy of inherent confinement effect and multiple Lewis acidic sites in nanocage. The "bimetallic cluster cutting" strategy for the construction of 3d-4f nanocages with large windows may represent a potential approach to develop supramolecular nanoreactor with high catalytic efficiency.