A series of coordination polymers constructed by a flexible tetracarboxylic acid: synthesis, structural diversity and luminescent properties

By using a flexible tetracarboxylic acid ligand, 5,5'-(p-xylylenediamino)-1,1', 3,3'-(benzene-tetra-carboxylic acid) (H4L), and three N-donor rigid co-ligands, ten coordination polymers, [Cu((4)bipy)(2)](H2L) (1), [Cd-2(L)(2bipy)(2)]center dot 5H(2)O (2), [Cd-2(L)(H2O)(6)]center dot 2H(2)O (3), [Mn-2(L)(H2O)(6)]center dot 4H(2)O (4), [Co-2(L)(H2O)(6)]center dot 4H(2)O (5), [Zn-2(L)(2bipy)(2)]center dot 3H(2)O (6), [Zn-2(L)(phen)(2)]center dot 2H(2)O (7), [Ni-2(L)(2bipy)(2)(H2O)(2)]center dot 2H(2)O (8), and [Cu-2(L)(phen)(2)(H2O)(2)] (9), and [Zn-2(L)(phen)(2)(H2O)(2)] (10) (4bipy = 4,4'-bipyridine, 2bipy = 2,2'-bipyridine, and phen = 1,10-phenanthroline) have been synthesized and structurally characterized by elemental analysis, IR, single-crystal X-ray diffraction and thermogravimetric analysis. The single crystal of ligand H4L reveals that there are two pairs of hydrogen bonds between two H4L molecules, which lead to a 1-D linear supramolecular chain. Complex 1 shows a three-dimensional (3D) two-fold interpenetrated Cu2+-4bipy cationic host framework, [Cu(4bipy)(2)](2+) with the 4-connected dia net, in which there are 1-D guest supramolecular chains formed by the intermolecular hydrogen bonds between adjacent (H2L)(2-) anions. 2 has a two-dimensional (2D) 4-connected {4(4)center dot 6(2)} uninodal sql/Shubnikov tetragonal plane network. 3-10 display a new 2D 2-nodal (2,4)-connected network with a {8(4)center dot 12(2)}{8}(2) topology. Complexes 3-5, 9 and 10 generate a 3D supramolecular structure by the hydrogen bonds between adjacent layers. 6-8 form a 3D network through strong p. p stacking interactions between adjacent layers. The co-ligand effects on the complex structures are studied. Also, we investigate the solid-state luminescence of compounds H4L, 2-10 at room temperature.