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, [Cd₃(L)₂(H₂O)₆]·1.5H₂O·2EtOH·DMF (<b>1</b>, H₃L = 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine) and [Zn₃(L)₂(H₂O)₂]·3H₂O·TEA·2DMF (<b>2</b>), 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 <b>1</b> and <b>2</b> were thermally stable up to 250 °C. Gas sorption measurement indicates that compounds <b>1</b> and <b>2</b> exhibited selective sorption capabilities for CO₂ over CH₄ and N₂ and could adsorb considerable amounts of H₂ at low temperature. These two compounds also showed high sorption capabilities for water, methanol, and ethanol vapors. The highest adsorption amounts of compounds <b>1</b> and <b>2</b> 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 <b>1</b> and <b>2</b> exhibit blue shifts of 138 and 132 nm, respectively, compared to the free ligand