An Amino-Coordinated Metal-Organic Framework for Selective Gas Adsorption

A novel 3D porous metal organic framework, JUC-141, constructed by 5-aminoisophthalic acid and Cu(NO₃)₂, has been synthesized successfully. The carboxyl groups in the ligand coordinate to Cu²⁺ to form the classic Cu₂(COO)₄ paddle wheel SBU, and the assembly of the SBUs with the isophthalic acid moieties leads to a kagome lattice. Interestingly, the amino groups in the ligand also take part in the coordination and link to the dipole of the paddle wheel as pillars, thus forming a 3D porous framework with eea topology. The sizes of the channels are 5.2 Å in the direction of [111] and 10.9 Å in the direction of [001]. Gas sorption tests show that the CO₂ adsorption capacities of JUC-141 are 79.94 and 51.39 cm³ g^-1 at 273 and 298 K under 1 atm pressure, respectively. However, the N₂ adsorption capacities of JUC-141 are 13.90 and 6.76 cm³ g^-1 at 273 and 298 K under 1 atm pressure, respectively. IAST calculations indicate that the selectivity values of CO₂/N₂ are 21.62 at 273 K and 27.60 at 298 K under 101 kPa, respectively. Good selective adsorption of CO₂ over N₂ makes JUC-141 possible for CO₂ storage and separation.