Metal-Coordination-Assisted Folding and Guest Binding in Helical Aromatic Oligoamide Molecular Capsules

Angewandte Chemie - International Edition

5 years ago

Metal-Coordination-Assisted Folding and Guest Binding in Helical Aromatic Oligoamide Molecular Capsules

Muriel Pipelier, Guillaume Lautrette, Jacques Lebreton, Barbara Wicher, Ivan Huc, Virginie Blot, Didier Dubreuil, Yann Ferrand, Maxime Horeau

The development of foldamer-based receptors is driven by the design of monomers with specific properties. Herein, we introduce a pyridazine-pyridine-pyridazine diacid monomer and its incorporation into helical aromatic oligoamide foldamer containers. This monomer codes for a wide helix diameter and can sequester metal ions on the inner wall of the helix cavity. Crystallographic studies and NMR titrations show that part of the metal coordination sphere remains available and may then promote the binding of a guest within the cavity. In addition to metal coordination, binding of the guest is assisted by cooperative interactions with the helix host, thereby resulting in significant enhancements depending on the foldamer sequence, and in slow guest capture and release on the NMR time scale. In the absence of metal ions, the pyridazine-pyridine-pyridazine monomer promotes an extended conformation of the foldamer that results in aggregation, including the formation of an intertwined duplex. Better together: Combined contributions from organic and inorganic components promote guest binding in helical containers formed from aromatic foldamers (red). Pyridazine-pyridine-pyridazine diacid building blocks can sequester metal ions on the inner wall of the helix cavity that may promote the binding of a guest within the cavity. In addition to metal coordination, binding of the guest is assisted by cooperative interactions with the helix host.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/anie.201701693