Anion binding of a bis(pyridylcarbamate) receptor bearing a diethylene glycol spacer

A flexible bis(pyridylcarbamate) receptor, 3-pyridyl-carbamic-acid-oxydi 1,2-ethanediylester (L²) and the anion complexes (1 -3) of the doubly protonated ligand ([L²H₂]²⁺) with ClO₄^-,SO₄^2- and Cl^- are reported. The binding modes of [L²H₂]²⁺ with the anions in 1-3 in the solid state are established by X-ray single crystal diffraction. Compounds 1 and 3 feature intriguing anionic polymer fashions. In compound 1, two zigzag perchlorate-water chains are encapsulated in the 1D channel constructed by 2+2 (2[L²H₂]²⁺ + 2ClO₄^-) hydrogen-bonded macrocycles, while in 3 the chloride ions are trapped on the wall of the hydrogen-bonded 1D channel formed by two U-shaped ligands. For compound 2, the packing diagram displays a corrugated layer structure, with the sulphate ions and the water molecules located between the layers. Receptor L² crystallises with perchlorate from the acid mixture HClO₄, H₂SO₄ and HCl.