A one-dimensional heterometallic coordination polymer with a three-dimensional supramolecular framework: poly[μ2-aqua-diaqua(2,2'-bipyridyl)(μ5-2-sulfonatobutanedioato)copper(II)sodium(I)].

The title compound, [CuNa(C(4)H(3)O(7)S)(C(10)H(8)N(2))(H(2)O)(3)](n), consists of one Cu(II) cation, one Na(I) cation, one 2-sulfonatobutanedioate trianion (SSC(3-)), one 2,2'-bipyridyl (bpy) ligand and three coordinated water molecules as the building unit. The coordination of the Cu(II) cation is composed of two pyridyl N atoms, one water O atom and two carboxylate O atoms in a distorted square-pyramidal coordination geometry with an axial elongation. The Na(I) cation is six-coordinated by three water molecules and three carboxylate O atoms from three SSC(3-) ligands in a distorted octahedral geometry. Two SSC(3-) ligands link two Cu(II) cations to form a Cu(2)(SSC)(2)(bpy)(2) macrocyclic unit lying across an inversion centre, which is further linked by Na(I) cations via Na-O bonds to give a one-dimensional chain. Interchain hydrogen bonds link these chains to form a two-dimensional layer, which is further extended into a three-dimensional supramolecular framework through π-π stacking interactions. The thermal stability of the title compound has also been investigated.