New Metal-Organic Frameworks Constructed from the 4-Imidazole-Carboxylate Ligand: Structural Diversities, Luminescence, and Gas Adsorption Properties

Reactions of metal ions with a rigid linear ligand 4-H(2)IBA incorporating 4-imidazolyl and carboxylate functional groups [4-H(2)IBA = 4-(1H-imidazol-4-yl)benzoic acid] under variable reaction conditions gave 11 new coordination polymers, [Cu(4-HIBA)(2)(H2O)(4)] (1), [(CuCuI)-Cu-II(4-HIBA)-(4-IBA)(H2O)(2)]center dot 2.3H(2)O (2), [Cu(4-HIBA)(Cl)] (3), [Cu-3(4-HIBA)(6)]center dot 7.8H(2)O (4), [Cd(4-HIBA)(2)(H2O)]center dot 2H(2)O (5), [Cd(4-HIBA)(2)] (6), [Cd(4-HIBA)(2)] center dot 2DMF (7), [Cd-2(4-HIBA)(4)]center dot H2O (8), [Zn(4-HIBA)(2)].H2O (9), [Zn(4-HIBA)(2)]center dot C2H5OH center dot DMF (10), and [Co(4-HIBA)(2)]center dot 2DMF (11). The copper complexes 1-4 are discrete molecules to three-dimensional (3D) infinite networks. Complexes 1 and 2 formed in different reaction temperatures exhibit a mononuclear motif and one-dimensional (1D) chain, respectively. Compounds 3 and 4 were obtained through controlling reaction solvent systems, and 3 features a two-dimensional (2D) (4,4) network by taking the binuclear [Cu-2(Cl)(2)] as 4-connecting nodes, whereas 4 is a 3-fold interpenetrating mog net with Point (Schlafli) symbol of (4.6(4).8)(2)(4(2).6(2).8(2)). The 4-HIBA(-) ligands act as rod-type two-connectors to connect metal Cd(II) centers into 4-connected 3D frameworks with different topologies: binodal 4-connected network with a Point (Schlafli) symbol of (8(6)) (5) and uninodal (6(5).8) net (6), uninodal 4-connected [2 + 2] interpenetrating (6(6)) dia net (7), and 5-fold interpenetrating dia net (8), respectively. Complex 9 has a 1D double chain structure, while 10 and 11 are isostructural as 7. Fluorescence and gas adsorption properties of the compounds have also been explored.