Single- and Double-Layer Structures and Sorption Properties of Two Microporous Metal-Organic Frameworks with Flexible Tritopic Ligand

Two 2D multifunctional microporous metal organic frameworks, [Cd-3(L)(2)(H2O)(6)]center dot 1.5H(2)O center dot 2EtOH center dot DMF (1, H3L = 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine) and (Zn-3(L)(2)(H2O)(2 center dot)3H(2)O center dot TEA center dot 2DMF (2), with single- and double-(6,3)-layer structures, respectively, have been synthesized by the reaction of Cd(Zn) nitrate with H3L in a mixed solvent of DMF, ethanol, and H2O. TGA and PXRD analysis showed that compounds 1 and 2 were thermally stable up to 250 degrees C. Gas sorption measurement indicates that compounds 1 and 2 exhibited selective sorption capabilities for CO2 over CH4 and N-2 and could adsorb considerable amounts of H-2 at low temperature. These two compounds also showed high sorption capabilities for water, methanol, and ethanol vapors. The highest adsorption amounts of compounds 1 and 2 are 168.8 and 257.3 cc/g for H2O, 175.1 and 140.8 cc/g for methanol, and 91.7 and 76.2 cc/g for ethanol, respectively. Furthermore, the maximum luminescence emission peaks of compounds 1 and 2 exhibit blue shifts of 138 and 132 nm, respectively, compared to the free ligand.