A heterometallic metal-organic framework based on multi-nuclear clusters exhibiting high stability and selective gas adsorption

The design and synthesis of porous heterometallic metal-organic frameworks (MOFs) with high thermal and chemical stability is a challenging task at present. In this work, by the heterometallic cooperative crystallization (HCC) approach, an original heterometallic MOF based on a tetra-carboxylic ligand has been solvothermally synthesized [In6O3Tb3O(CBDA)3]center dot 18DMF center dot 3H(2)O (In/Tb-CBDA) [CBDA = 5,5'-(carbonylbis (azanediyl))-diisophthalic acid, DMF = N, N-dimethylformamide]. The framework of In/Tb-CBDA is cooperatively assembled from the rarely reported tetra-nuclear In4O2(COO)(4) and tri-nuclear Tb3O(COO)(6) clusters, and an organic ligand. Topological analysis indicates that In/Tb-CBDA exhibits a new (4,4,6)-connected topology with the Schlafli symbol (4.6(3).8(2))(6)(4(3.)6(9).8(3))(2)(6(2).8(4))(3). Noteworthy, forming multinuclear metal clusters prompts the framework to maintain high stability under the conditions of heating to 150 degrees C, exposure to air, and soaking in acidic and basic aqueous solutions for 12 h. After desolvation, In/Tb-CBDA shows permanent porosity proved by N-2 adsorption isotherms. In addition, theoretical ideal adsorption solution theory (IAST) calculation indicates that In/Tb-CBDA displayed high selective adsorption of CO2/CH4, C2H6/CH4 and C3H8/CH4 at room temperature. This work shows a striking example of a porous heterometallic MOF material with high thermal and chemical stability, which exhibits high-efficiency selective gas adsorption behaviour.