Mechanochemical synthesis of bent metallacycles and confinement catalysis in the solid-state

Abstract

Synthetic cages or capsules serve as versatile container molecules capable of facilitating host–guest chemistry and confinement-driven catalysis, akin to natural enzymes. However, their guest-binding cavities are typically formed concurrently with their discrete frameworks. In this study, we demonstrate that bent metallacycles, Pd₂L₂, structurally analogous to partial constructs of discrete coordination capsules Pd₂L₄, can be effectively synthesized mechanochemically. Crystallographic analysis revealed that these structures would self-assemble into non-covalent coordination capsules with tunable interior cavity dimensions. They were further utilized in solid-state, confinement-directed C–C bond formation catalysis, where they exhibited enhanced substrate size/shape recognition capabilities, compared to common organic base catalysts.