cg900788h_si_003.cif (92.13 kB)

Co(II) Metal−Organic Frameworks (MOFs) Assembled from Asymmetric Semirigid Multicarboxylate Ligands: Synthesis, Crystal Structures, and Magnetic Properties

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posted on 02.12.2009, 00:00 by Hailong Wang, Daopeng Zhang, Daofeng Sun, Yuting Chen, Li-Fang Zhang, Laijin Tian, Jianzhuang Jiang, Zhong-Hai Ni
A series of four new coordination polymers, namely, [Co(HL1)(μ-4,4′-bpy)(H2O)3]n·(4,4′-bpy)n·(H2O)2n (1), [Co1.5(L2)(μ-4,4′-bpy)1.5]n·(4,4′-bpy)0.5n (2), [Co3(L3)(HL3)(OH)(H2O)2(μ-4,4′-bpy)2]n·(H2O)2.5n (3), and [Co1.5(L4)(μ-4,4′-bpy)2(H2O)3]n·(H2O)3n (4), have been assembled from four asymmetric semirigid multicarboxylate ligands 3-(4-carboxy-phenoxy)-phthalic acid (H3L1), 3-(2-carboxy-phenoxy)-phthalic acid (H3L2), 4-(2-carboxy-phenoxy)-phthalic acid (H3L3), and 4-(4-carboxy-phenoxy)-phthalic acid (H3L4) with the help of 4,4′-bipyridine (4,4′-bpy) ligand. X-ray single crystal diffraction analysis reveals that compound 1 displays a one-dimensional (1D) zigzag chain structure constructed from 4,4′-bpy ligands and partly deprotonated L1 ligands, which further forms a three-dimensional (3D) supramolecular architecture via hydrogen bonds. Complex 2 possesses a two-dimensional (2D) layered architecture composed of continuous trinuclear Co(II) clusters. Complex 3 also shows a 2D molecular framework assembled from alternate tetranuclear and dinuclear Co(II) clusters bridged by 4,4′-bpy or L3 ligands, and complex 4 exhibits a 3D (4,4)-connected self-penetrating network constructed from ladder-like and fishbone-like subunits. Magnetic studies indicate the spin−orbit coupling of isolated Co(II) in 1 and the overall antiferromagnetic interaction in 24.