Six Co(II) Coordination Polymers Based on Two Isomeric Semirigid Ether-Linked Aromatic Tetracarboxylate Acid: Syntheses, Structural Comparison, and Magnetic Properties

Six Co(II) coordination polymers including {[Co-5(L-1)(2)(bibp)(2)]center dot bibp}(n) (1), {[Co-2(L-1)(bibp)(2)center dot 2H(2)O}(n) (2), {[Co-2(Li)(bimmb)(2)].DMF}(n) (3), [Co-2(L-1)(bimb)center dot 3H(2)O](n) (4), [Co(L-2)(bibp)(H2O)](n) (5), and [Co-2(L-2)(bimb)](n) (6) (H4L1/H4L2 = 5,5'-(1,4/1,3-phenylenebis(methox-y))-diisophthalic acid, bibp = 4,4'-bis(imidazolyl)biphenyl, bimmb = 1,4-bis(imidazol-1-ylmethyl)benzene, and bimb = 1,4-bis(lmidazol) butane) were synthesized under solvothermal conditions and structurally characterized. Complexes 1 and 2 are cocrystallized in a one-pot reaction with significant differences in the structures. Complex 1 exhibits a three-dimensional (3D) metal organic framework composed of an interesting pentanuclear [Co-5(mu(3)-O)(2)N-4(COO)(8)](2-) cluster. Complex 2 shows a 3D 4-fold interpenetrated bbf topological framework. Complex 3 has a two-dimensional (2D) zigzag network, three of which further interpenetrate each other, reconstructing a 2D + 2D -> 2D network with new-topology. Complex 4 shows' a novel topological 3D framework with a [Co-2(COO)(3)(H2O)(3)N-2] cluster. Complex 5 exhibits a new topological framework with the point symbol [4(4).6(2)] [4](2). And complex 6 displays [Co-2(COO)(2)(bimb)] binuclear secondary building units based on sql framework with the point symbol [4(4).6(2)]. Variable-temperature magnetic studies indicate that complexes 1, 4, and 6 exhibit antiferromagnetic couplings between carboxyl-bridging Co(II) ions.