Supramolecular interactions in a family of dinuclear helicates in the solid-state

ABSTRACT

Metallo-helicates are a commonly encountered assembly within supramolecular chemistry. Interest in these architectures stems from their inherent helical chirality which positions them for a diverse range of applications such as catalysis and non-linear optics (NLO). The current study uses Co(II) dinuclear double helicates as versatile supramolecular synthons. The ditopic ligand, L, features two tridentate quinolinyl-hydrazone binding sites imparting it with hydrogen bond donors and π-faces for secondary supramolecular interactions. Incorporation of L into [Co₂(L)₂]⁴⁺ helical assemblies results in a helical cationic supramolecular synthon with moieties predisposed to forming π-π stacking and hydrogen bond interactions. The single-crystal X-ray structures of [Co₂(L)₂]X₄ (X = ClO₄ ^?, BF₄ ^? and CF₃SO₃ ^?) revealed a variety of anion dependent hydrogen bond networks arising through the interaction of the hydrazide hydrogen with the anion. These interactions in turn strongly influence the nature of the π-π stacking interactions of the quinoline moieties which can be analysed via the Hirshfield surface.