Binuclear, 2D grid and 3D interlocking coordination polymers based on 1,2,4,5-benzenetetracarboxylic acid and 4,4′-azobispyridine

Three new nickel(II) complexes [Ni2(btec)(azopy)2(H2O)8]·2H2O (1), {[Ni(H2btec)(azopy)(H2O)2]·(azopy)}n (2) and {[Ni4(btec)2(azopy)3(H2O)10]·8H2O}n (3) (H4btec = 1,2,4,5-benzenetetracarboxylic acid; azopy = 4,4′-azobispyridine) have been synthesized by tuning the reaction temperature and the metal–ligand ratio. They were characterized by single-crystal X-ray diffraction and elemental analysis. 1 shows a binuclear structure, 2 exhibits a 2D grid, and 3 features an interesting 3D framework with (63)(4.62)(42.62.82) topology formed by two types of interlocked 2D layers.