Poster Presentation The 35th Biennial Conference of the Society of Crystallographers in Australia and New Zealand 2024 (Crystal 35)

Metallosupramolecular cages are a promising class of discrete molecular containers that exhibit highly selective guest encapsulation for applications in molecular separations,¹ catalysis² and the stabilisation of reactive species.³ The rational design of organic ligand binding modes and corresponding metal coordination geometries leads to the predictable self-assembly of complex architectures. Metallosupramolecular cages enclose a central cavity that features a distinct microenvironment for host-guest interactions.

In this study, a [Zn₂L₃]⁴⁺ helicate was self-assembled from zinc triflimide and the ligand (L = 6,6'-bis(1-ethyl-1H-benzo[d]imidazol-2-yl)-3,3'-bipyridine), as the triflimide anion is too large to template the formation of a tetrahedral cage. Subsequent addition of a suitable anionic template (X^- = CF₃SO₃^-, BF₄^-, PF₆^-, ClO₄^-, Cl^-, Br^-, I^-) triggers reassembly of the [Zn₂L₃]⁴⁺ helicate into an [X^- ⊂ Zn₄L₆]⁷⁺ tetrahedron upon encapsulation of the anionic guest. The encapsulated anion can be further exchanged for a non-templating neutral tetrahedral guest (G = CCl₄, CBr₄, CHCl₃) to produce [G ⊂ Zn₄L₆]⁸⁺. Thus, we report the successful templation of a [Zn₂L₃]⁴⁺ helicate into an [X^- ⊂ Zn₄L₆]⁷⁺ tetrahedron via anion encapsulation, followed by further guest exchange with a non-templating neutral guest to form [G ⊂ Zn₄L₆]⁸⁺ and investigate the intriguing guest binding interactions of this system.