Syntheses, Gas Adsorption, and Sensing Properties of Solvent-Controlled Zn(II) Pseudo-Supramolecular Isomers and Pb(II) Supramolecular Isomers

On the basis of the bifunctional 1,4-bis(imidazol-1-yl)terephthalic acid (H2BTA), four three-dimensional (3D) Pb(II)/Zn(II) coordination polymers (CPs), {[Zn(BTA)]·1.5(DOA)}n (1), [Zn(BTA)]n (2), [Pb(BTA)]n (3), and [Pb(BTA)]n (4), have been synthesized (DOA = dioxane). Structural analyses reveal that two Zn(II)-based complexes are 3D (4,4)-c pts pseudo-supramolecular isomers for 1 and 2, and two Pb(II)-based complexes are supramolecular isomers with a 3D (4,5,6)-c net for 3 and a 3D 6-c pcu net for 4, respectively. Furthermore, the gas adsorption behaviors of complexes 1 and 2 for N2, CO2, and CH4 have been studied in detail at varying temperatures, and the results showed that the adsorption capacities to CO2 at 273 K and 1 bar are stronger than those of other gases. Meanwhile, the selectivity of 1 and 2 for CO2/CH4 was evaluated by the usage of the ideal adsorbed solution theory, whose selectivity exceeded those of reported MOFs under similar conditions. In addition, the fluorescent measurements showed ...