Anion-directed assembly of supramolecular zinc(II) halides with N,N′-bis-4-methyl-pyridyl oxalamide

We report here the supramolecular structures and solid state luminescence of zinc(II) halides with N,N'-bis-4-methyl-pyridyl oxalamide (L), where the supramolecular assembly formed is dependent on the halide, and led to the formation of one-dimensional coordination polymers for Cl ([ZnCl2(L)](n)) and Br ([ZnBr2(L)](n)) or a discrete macrocycle for I ([ZnI2(L)](2)), respectively. The rectangular structure of iodo compounds with pyridyl amide L shows an interesting nanotube framework built from pi center dot center dot center dot pi interactions in combination with hydrogen bonding. To our knowledge, these are rare examples of the anion-directed assembly of supramolecular structures. The low energy emission at ca. 500 nm for [ZnI2(L)](2) is assigned to a ligand-to-metal charge-transfer (LMCT) transition.