Three new coordination polymers based on an N-heterocyclic carboxylic acid: Structural diversity, luminescent properties and gas adsorption

Based on a mixed-ligand strategy, three new coordination polymers (CPs), namely {[Zn2(TZMB)2(bim)]·2DMA·EtOH}n (1), {[Zn2(TZMB)2(4,4′-bibp)·2DMA·EtOH]}n (2), and {[Cd(TZMB)(bbibp)] DMA·EtOH}n (3), (bim = benzimidazole, 4,4′-bipb = 4,4′-bis(pyrid-4-ly)biphenyl, bbibp = 4,4′-bis(benzoimidazo-1-ly)biphenyl, DMA = N, N-dimethylacetamide), have been successfully synthesized by the reaction of 4,4'-(1H-1,2,4-triazol-1-yl)methylenebis (benzonic acid) (H2TZMB) and Zn(II)/Cd(II) under the solvothermal methods. The structural analyses indicate that 1 displays 2-nodal (3,4)-c 3D framework with a {63}{65.8} topology, 2 exhibits a rare 1D ​+ ​1D → 3D framework with the same topology as 1, and 3 is a 3D supramolecular framework obtained by π … π stacking interaction between the adjacent 2D layers with the topology of {65.8}. Furthermore, the luminescent experiments indicate that 1 and 2 exhibit high sensitivity and selective detection towards Fe3+ ions with the low detection limit of 7.15 × 10−4 M−1 and 2.56 × 10−4 M−1, respectively. Gas adsorption behaviors show the adsorption amounts of 3a for CO2 advantage over those of CH4 and N2. The selectivities of 3a for CO2/CH4 were estimated by the ideal adsorbed solution theory (IAST), which are 4.78 for land fill gas (CO2:CH4 = 0.50:0.50) and 1.39 for natural gas (CO2:CH4 = 0.05:0.95), respectively. Finally, the luminescent quenching mechanisms are also discussed in detail.