Simple 1:1 and 1:2 complexes of metal ions with heterocycles as building blocks for discrete molecular as well as polymeric assemblies

The use of transition metals with low coordination numbers or blocked bonding positions in combination with nitrogen heterocyclic ligands of different geometries (e.g. pyrazole, imidazole, bipyrazine, pyrimidine or purine) leads to formation of both discrete supramolecular assemblies and 1D polymers. When highly coordinating ‘naked’ metal ions are applied instead, 2D and 3D frameworks are generated. Some of the assemblies, both molecular and polymeric, possess cavities or channels that can reversibly include guest molecules, including anions. The chemistry reported provides a vast playground for potential applications and future synthetic work.