Supramolecular Circular Helicates Formed by Destabilisation of Supramolecular Dimers

The effect of changes in the angles at the connection points of linear/circular helicates is explored as a route to control the nuclearity and architecture of metallo-supramolecular arrays. This effect is probed by changing the geometry of the metal centre used to assemble bis-pyridylimine ligands that contain a 1,3-bis(aminomethyl) benzene spacer group. Tetrahedral metal ions favour linear dimers, whereas octahedral nickel(II) predominantly gives a triangular circular helicate. Five-coordinate copper(II) falls in the middle of these extremes and results in the formation of solvent-dependent mixtures of dimer and trimer. The trinuclear, triangular, circular helicate structures, which result from coordination to copper(II) and nickel(II), are structurally characterised by X-ray crystallography and reveal that the units can aggregate into hexagonal arrays that contain anion-filled tube-like channels in the solid state.