Title
Asymmetric catalysis mediated by a mirror symmetry-broken helical nanoribbon
Author
Zhaocun Shen, Yutao Sang, Tianyu Wang, Jian Jiang, Yan Meng, Yuqian Jiang, Kou Okuro, Takuzo Aida, Minghua Liu
Year
2019
Journal
Nature Communications
Abstract
Although chirality has been recognized as an essential entity for life, it still remains a big mystery how the homochirality in nature emerged in essential biomolecules. Certain achiral motifs are known to assemble into chiral nanostructures. In rare cases, their absolute geometries are enantiomerically biased by mirror symmetry breaking. Here we report the first example of asymmetric catalysis by using a mirror symmetry-broken helical nanoribbon as the ligand. We obtain this helical nanoribbon from a benzoic acid appended achiral benzene-1,3,5-tricarboxamide by its helical supramolecular assembly and employ it for the Cu2+-catalyzed Diels–Alder reaction. By thorough optimization of the reaction (conversion: > 99%, turnover number: ~90), the enantiomeric excess eventually reaches 46% (major/minor enantiomers = 73/27). We also confirm that the helical nanoribbon indeed carries helically twisted binding sites for Cu2+. Our achievement may provide the fundamental breakthrough for producing optically active molecules from a mixture of totally achiral motifs.
Full Article
Instrument
V-550, CPL-200, J-810
Keywords
Circular dichroism, Stereochemistry, Absorption, Ligand binding, Circularly polarized luminescence, Nanostructures, Materials