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

Abstract

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 π⋯π 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.