Environmental control in the assembly of metallomacrocycles and one-dimensional polymers with 4,2′:6′:4′′-terpyridine linkers and zinc(ii) nodes

Abstract

Room temperature crystallization experiments have been carried out by layering to investigate the assemblies produced from combinations of ZnCl₂ and 4′-(4-(naphth-1-yl)phenyl)-4,2′:6′,4′′-terpyridine (1) or 4′-(2′,3′,4′,5′,6′-pentafluorobiphenyl-4-yl)-4,2′:6′,4′′-terpyridine (2) in the presence of the potential inclusion guests anthracene, pyrene or perylene. The reactions lead to the formation of the discrete metallohexacycle [{ZnCl₂(1)}₆] when anthracene or perylene is present, but ¹H NMR spectroscopic studies confirm that neither molecule is incorporated as a guest in the lattice. When pyrene is present, a one-dimensional coordination polymer [ZnCl₂(1)]_n with a crenellated topology assembles, and under the same crystallization conditions, a structurally analogous polymer [ZnCl₂(2)]_n can also be isolated. In these structures, pyrene is included as a guest, along with 1,2-dichlorobenzene used as a solvent for the crystallizations. The formation of the polymer [ZnCl₂(2)]_n competes with that of the metallosquare [{ZnCl₂(2)}₄]. The metallohexacycles and metallosquare assemble into tube-like arrays, generating highly porous lattices from which solvent loss is facile. In contrast to the topologies of the one-dimensional chains in [ZnCl₂(1)]_n and [ZnCl₂(2)]_n, the one-dimensional coordination polymer [ZnI₂(1)]_n is built up along a glide plane; stacking of the chains through head-to-tail pairings of ligands produces corrugated sheets which pack efficiently in the lattice.