Syntheses, structures and properties of two coordination polymers based on 3,5-di(4H-1,2,4-triazol-4-yl)benzoic acid with multicarboxylates as mixed ligands

Two zinc coordination polymers, namely {[Zn-6(L)(6)(P-BDC)(3)]center dot 4(H2O)}(n) (1) and {[Zn-2(H2O)(3)(L)(1,2,3-BTC)]}(n) (2) {HL = 3,5-di(4H-1,2,4-triazol-4-yl)benzoic acid, H(2)p-BDC = 1,4-benzenedicarboxylic, 1,2,3-H3BTC = 1,2,3-benzenetricarboxylic acid), were synthesized under solvothermal conditions. Single-crystal X-ray analyses show that complex 1 exhibits two-dimensiOnal (2D) double-layered 3,4L88 nets, which further generate a 2D -> 3D supramolecular structure. Complex 1, with H(2)p-BDC as the mixed ligand, owns a interpenetrated structure with the (6(3))(6(6))4(6(9).8) topology built by pi -pi interactions. When the mixed ligand is changed from the dicarboxylate H(2)p-BDC to the tricarboxylate 1,2,3-H3BTC in complex 2, each [L](-) anion in 2 acts as a tridentate ligand, linking three Zn(II) ions, and each [1,2,3-BTC](3-) anion in 2 links four Zn(II) ions. Consequently, a different (3.4(2))(3.4(3).5.6)(3(2).4(3).5(4).6(7).7(3).8(2))(3(2).4(4).5(3).6(4).7(2)) topological network is formed in complex 2. The two complexes have also been characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction and thermogravimetry measurements. It is also found that the fluorescence of complexes 1 and 2 could be quenched by nitroaromatics (NACs), indicating their potential application as sensory materials. (C) 2017 Elsevier Ltd. All rights reserved.