Zinc(II) coordination polymers with mixed ligands: Synthesis, structures and evaluation on metal sensing

Reactions of the Zn(II) salts with benzene-1,3,5-tricarboxylic acid (1,3,5-H3BTC) and bis-pyridyl-bis-amide (bpba) ligands with different flexibility, N,N '-bis(3-pyridylmethyl)oxalamide (L-1), N,N '-bis(3-pyridylmethyl) adipoamide (L-2) and N,N '-bis(3-pyridylmethyl)sebacoamide (L-3), under hydrothermal conditions afforded [Zn(L-1)(0.5)(1,3,5-HBTC)(H2O)(2)](n), 1, {[Zn(L-2)(0.5)(1,3,5-HBTC)(H2O)]center dot H2O}(n), 2, [Zn-2(L-3)(0.5)(1,3,5-BTC)(OH)](n), 3, and {[Zn(L-3)(1,3,5-HBTC)]center dot 2H(2)O}(n), 4, displaying a 1D looped chain, a 2D layer with the 3,4L83 topology, a 3D net with the 3,3,5T33 topology and a 2-fold interpenetrated 2D layer with the sql topology, respectively, and indicating that their structural diversity is dependent on the ligand flexibility and the solvent system. The investigation on the sensing properties of complexes 2 - 4 reveals that 3 manifests stability in aqueous environments and show high selectivity toward sensing of the Fe3+ ion.