Mesomeric metallosupramolecular grid architectures

Abstract

We describe herein the self-assembly processes as well as the structural properties of metallosupramolecular grid-architectures, involving bis-bidentate ligand 1, based on imino-pyridine complexation subunits and tetrahedrally (Cu+, Ag+) and octahedrally (Co2+, Zn2+, Fe2+) coordinated metal ions. The NMR, electrospray ionisation mass spectrometry data and X-ray crystal structure results suggest that in solution corner- and grid-type compounds are present, while in the solid state they adopt very compact and stable [2 × 2] grids arrays. Despite the variable binding behaviours of tetrahedrally coordinated cations (Cu+, Ag+) and the four coordination (lower) number of octahedrally coordinated cations (Co2+, Zn2+, Fe2+), the flexibility of the ligand 1 induce a perfect arrangement of these components, resulting in the formation of metallosupramolecular grids. Examination of such structures suggests that simple conformational rotation around the central phenyl of ligand 1 results in the self-assembly of chiral ligands. This allows the formation of mesomeric grid-type superstructures containing an inversion centre with half-superior and -inferior inner surfaces of opposite chirality.