Loading linear arrays of Cu(II) inside aromatic amide helices

The very stable helices of 8-amino-2-quinolinecarboxylic acid oligoamides are shown to uptake Cu(II) ions in their cavity through deprotonation of their amide functions with minimal alteration of their shape, unlike most metallo-organic structures which generally much differ from their organic precursors. The outcome is the formation of intramolecular linear arrays of a defined number of Cu(II) centers (up to sixteen in this study) at a 3 Å distance, forming a molecular mimic of a metal wire completely surrounded by an organic sheath. The helices pack in the solid state so that the arrays of Cu(II) extend intermolecularly. Conductive-AFM and cyclic voltammetry suggest that electrons are transported throughout the metal-loaded helices in contrast with hole transport observed for analogous foldamers devoid of metal ions.