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

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.