Seven new metal-organic frameworks assembled from semi-rigid polycarboxylate and auxiliary N-donor ligands: syntheses, structures and properties.

Seven new metal-organic frameworks (MOFs), namely, [Zn(L)(HO)] (1), [Zn(L)(dib)(HO)] (2), {[Zn(L)(4,4'-bipy)(HO)]·HO} (3), [Cd(L)(1,10-phen)] (4), [Ni(HL)(4,4'-bipy)(μ-OH)(μ-HO)] (5), {[Co(L)(4,4'-bibp)]·(4,4'-bibp)} (6), and [Co(L)(4,4'-bibp)(HO)] (7), where HL and HL are semi-rigid 3-(3,5-dicarboxylphenoxy)phthalic acid and 4-(3,5-dicarboxylphenoxy)phthalic acid, respectively, and 4,4'-bipy is 4,4'-bipyridine, dib is 1,4-bis(1H-imidazol-1-yl)benzene, 1,10-phen is 1,10-phenanthroline and 4,4'-bipb is 1,4-bis(pyridin-4-yl)benzene, have been prepared under solvothermal conditions with Zn, Cd, Co and Ni ions in the presence of auxiliary N-donor ligands. The crystal structures and photoluminescence and magnetic properties of these compounds have been investigated. Compound 1 displays a 3,4,6-connected two-dimensional (2D) topology with a Schläfli symbol of (4.5)(4.5.7)(4.5.6), and the 2D structure was further assembled to form a three-dimensional (3D) framework by intermolecular O-H...O hydrogen bonds. Compound 2 features a novel 3,3,4-connected structure and the point symbol is (4.10)(4.6.8)(6.8). Compound 3 exhibits a 3,4,6-connected 3-nodal net having a 3,4,6 T53 type topology, with the point symbol (4.6)(4.6)(4.6.8.10). Compound 4 shows a 2D→3D supramolecular structure formed by π-π stacking interactions. Compound 5 possesses a 3D framework with a tfz-d net topology. Compounds 6 and 7 are constructed from the same auxiliary ligand and metal salt at the same temperature, but with different main ligands and exhibiting different topologies. Compound 6 presents a 3D 4,6-connected topological network with a Schläfli symbol of (3.4.6)(3.4.5.6), while compound 7 has a 3D topological network with a Schläfli symbol of (4.6). Magnetic analyses indicate that compounds 5 and 7 show weak antiferromagnetic interactions.