Zinc-seamed pyrogallol[4]arene dimers as structural components in a two-dimensional MOF

Abstract

The synthesis of a two-dimensional (2D) metal–organic framework (MOF) is described wherein Zn-seamed pyrogallol[4]arene (PgC_x) nanocapsules are utilized as supramolecular building blocks with 4,4′-bipyridine (bpy) linkers. The choice of linker and of crystallization solvent (DMSO) was guided by electronic structure calculations on the zinc model complexes Zn(C₂H₃O₂)₂L, which showed that bpy and DMSO have similar Zn–L binding strengths and that there is little drop-off in binding strength when bpy is bound to a second Zn(C₂H₃O₂)₂ moiety. The MOF features unusual coordination geometries at the zinc centres along the nanocapsular periphery when compared to previous examples of zinc-seamed nanocapsules. The change in coordination geometry leads to a compulsory change in the internal volume of the nanocapsule as well as the behaviour of the encapsulated guest molecule. There are also several well defined voids and channels within the structure.