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

Abstract

Six Co(II) coordination polymers including {[Co5(L1)2(bibp)2]·bibp}n (1), {[Co2(L1)(bibp)2·2H2O}n (2), {[Co2(L1)(bimmb)2]·DMF}n (3), [Co2(L1)(bimb)·3H2O]n (4), [Co(L2)(bibp)(H2O)]n (5), and [Co2(L2)(bimb)]n (6) (H4L1/H4L2 = 5,5′-(1,4/1,3-phenylenebis(methoxy))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 [Co5(μ3-O)2N4(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 [Co2(COO)3(H2O)3N2] cluster. Complex 5 exhibits a new topological framework with the point symbol [44.62] [4]2. And complex 6 displays [Co2(COO)2(bimb)] binuclear secondary building units based on sq1 framework with the point symbol [44.62]. Variable-temperature magnetic studies indicate that complexes 1, 4, and 6 exhibit antiferromagnetic couplings between carboxyl-bridging Co(II) ions.