Mesoporous assembly of homochiral aluminum molecular rings for room-temperature asymmetric cyanosilylation

Chiral metal-organic macrocycles and cages, as enzyme-mimetic platforms for asymmetric catalysis, face the challenge of integration with low-cost metals. We report the first homochiral Al lII macrocycle-based supramolecular cages, cAlOC-185- S/R —[(c-Al 8 ) 6 ], synthesized via a dual-ligand strategy combining chiral phosphates and N-donor co-ligands with HNO 3 . A distinctive trait is water coordination at the macrocycle’s waist, exposing catalytic sites. Additionally, switching N-donor coligands from NA to 6-NH 2 -NA modulates supramolecular assembly, enlarging the external channel diameter from 2.3 to 3.3 nm. Compared with traditional metal-organic cages, these macrocycle-based systems offer three key advantages. (1) Cost-effective: accessible ligands, low-cost Al III , one-pot synthesis. (2) Improved mass transfer: substrates react on the surface (no cage entry). (3) Tunable supramolecular channels. Benefiting from these structural and pore-regulating features, their benzaldehyde cyanosilylation efficiency is significantly enhanced: from 48 h, 91% yield, 82% ee to 12 h, nearly quantitative yield, 90% ee (rt), far outperforming free ligands (14% yield, no ee). Notably, most reported catalysts require −78 °C to 0 °C, with only ∼10% active at rt. Theoretical calculations confirm that enantioselectivity arises from the energy-favorable pathway. With 100-gram-scale synthesis validating its scalability, this work provides a low-cost, high-performance Al III catalyst and a versatile platform for catalyst development via precise pore engineering and theoretical guidance.