<p>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<sup>lII</sup> macrocycle-based supramolecular cages, cAlOC-185-<i>S/R</i>—[(c-Al<sub>8</sub>)<sub>6</sub>], synthesized via a dual-ligand strategy combining chiral phosphates and N-donor co-ligands with HNO<sub>3</sub>. A distinctive trait is water coordination at the macrocycle’s waist, exposing catalytic sites. Additionally, switching N-donor coligands from NA to 6-NH<sub>2</sub>-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<sup>III</sup>, 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<sup>III</sup> catalyst and a versatile platform for catalyst development via precise pore engineering and theoretical guidance.</p>

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

  • Yi-Bo Chen,
  • Jian Hao,
  • Jia-Jia Liu,
  • Han Xiao,
  • Qi Lv,
  • Min-Yi Zhang,
  • Shangda Li,
  • Lisheng Chi,
  • Yu-Wu Zhong,
  • Laurent Ruhlmann,
  • Jian Zhang,
  • Chunsen Li,
  • Wei-Hui Fang

摘要

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 AllII macrocycle-based supramolecular cages, cAlOC-185-S/R—[(c-Al8)6], synthesized via a dual-ligand strategy combining chiral phosphates and N-donor co-ligands with HNO3. A distinctive trait is water coordination at the macrocycle’s waist, exposing catalytic sites. Additionally, switching N-donor coligands from NA to 6-NH2-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 AlIII, 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 AlIII catalyst and a versatile platform for catalyst development via precise pore engineering and theoretical guidance.