Metal Ion-Mediated\nSupramolecular Nanotube Catalyst\nfor Enantioselective Reactions

Rational\ncontrol over the morphologies of supramolecular assemblies\nfor asymmetric catalysis with enhanced enantioselectivity represents\na pivotal challenge in the realm of synthetic chemistry and material\ntechnology. Herein, Cu(II) ion-mediated supramolecular nanostructures\nassembled from chiral amino acid-based amphiphiles (l/d-AlaC<sub>16</sub>) are fabricated as chiral catalysts for\nDiels–Alder cycloaddition between aza-chalcone and cyclopentadiene.\nIn particular, compared with the supramolecular nanosheet formed by l/d-AlaC<sub>16</sub> without Cu(II) ions, we found\nthat the l/d-alanine chiral amphiphile can form\nsupramolecular nanotubes with a multilayer structure and with the\nthickness of the tubular wall about 15 nm through the transition from\na nanoribbon to tubular structure in the presence of Cu(II) ions.\nConsequently, the catalytic enantioselectivity of Diels–Alder\nwas improved from 6% (nanosheet) to 49% (nanotube), attributed to\nthe curved surface of the nanotube structure, which provides a preferential\nchiral environment and high density of the catalytic center to favor\nthe chirality transfer. Our study presented in this work offers valuable\ninsights for designing chiral supramolecular catalysts with a higher\nenantioselectivity driven by a metal ions-mediated nanostructure.