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 1, 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 x 11.37, 10.08 x 11.68 and 10.28 x 10.98 Angstrom 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 [M-16(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.