Structural diversity and magnetic properties of Co (II)/Mn(II)/Ni(II) coordination polymers constructed from an unsymmetrical tetracarboxylic acid and varying N-donor ligands

Seven new coordination polymers (CPs), namely, [M-2(alpha-bptc)(phen)center dot 2H(2)O]center dot 3H(2)O (M = Co, for 1; Mn, for 2), [M-2(alpha-bptc)(bpea)center dot 7H(2)O]center dot H2O (M = Co, for 3; Ni, for 4), [Co-3(alpha-Hbptc)(2)(4,4'-bipy)(2)center dot 4H(2)O]center dot 2H(2)O (5), [Co-4(alpha-bptc)(2)(bpee)(3)center dot 2H(2)O]center dot 2H(2)O (6), and [Ni-4(alpha-bptc)(4,4'-bipy)(2)(OH)(4) center dot 4H(2)O]center dot 13H(2)O (7) (alpha-H(4)bptc = 2,3,3',4'-biphenyl tetracarboxylic acid, phen = 1,10-phenanthroline, bpea = 1,2-bis(4-pyridyl) ethane, 4,4'-bipy = 4,4'-bipyridine, bpee = 1,2-bis(4-pyridyl)ethylene), based on an unsymmetrical tetracarboxylic acid with the aid of varying ancillary N-donor ligands have been synthesized under hydrothermal conditions. Interestingly, the unsymmetrical tetracarboxylate linked Co (II)/Mn (II)/Ni (II) ions to give diverse structural fragments, which were connected by various ancillary N-donor ligands, resulting in the formation of CPs with different structural topologies. Complexes 1 and 2 were isomorphous and showed a 1D tube-like [M-2(alpha-bptc)center dot 2H(2)O] network decorated with phen moiety. Complexes 3 and 4 were also isomorphous and displayed a 1D ladder-like chain structure assembled by [M-2(alpha-bptc)center dot 7H(2)O] metallacycles as nodes and bpea as linkers. Complex 5 featured a 3D CdS net with 4-connected (6(5)center dot 8) topology constructed by the combination of 1D [Co-3(alpha-Hbptc)(2)center dot 3H(2)O] zigzag chain and 4,4'-bipy. Complex 6 exhibited a novel 3D framework with (4,4,6)-connected (4(2)center dot 4(2)center dot 6) topology formed through the integration of [Co-2(alpha-bptc)center dot H2O] double layers with bpee. Complex 7 possessed a 3D bcu-x net with 4-connected (7(4)center dot 8(2)) topology, yielded by linking the 4,4'-bipy with left-and right-handed [Ni-4(alpha-bptc)(OH)(4)center dot 4H(2)O] helical chains. Magnetic susceptibility measurements indicated the ferromagnetic behaviours of complex 7.