Hydrothermal synthesis and crystal structures of three-dimensional co-ordination frameworks constructed with mixed terephthalate (tp) and 4,4′-bipyridine (4,4′-bipy) ligands: [M(tp)(4,4′-bipy)] (M = Co^II, Cd^II or Zn^II)

Three new metal-organic co-ordination frameworks formulated as [M(tp)(4,4′-bipy)] [M = Co^II l, Cd^II 2 or Zn^II 3; tp = terephthalate; 4,4′-bipy = 4,4′-bipyridine] have been hydrothermally prepared and structurally characterized. Each pair of metal atoms in the three compounds are bridged by bis-bidentate or chelating/bridging bis-bidentate tp ligands to form a linear or zigzag co-ordination chain, and adjacent chains are further linked by chelating or monodentate bis-bidentate tp ligands to form two-dimensional rectangular or parallelogram-like [M(tp)] sheets with dimensions of 10.30 × 11.37,10.08 × 11.68 and 10.28 × 10.98 A for complexes 1, 2 and 3, respectively. Adjacent sheets are pillared by 4,4′-bipy spacers into a three-dimensional co-ordination network through the covalently linking mode of ⋯ 4,4′-bipy-M^II-4,4′-bipy-M^II ⋯, which feature cuboidal [M16(tp)8(4,4′-bipy)₈] structural units. Twofold interpenetration of the above three-dimensional co-ordination networks results in stable crystal structures of the three compounds.