A Polyhedron-Based Heterometallic MOF Constructed by HSAB Theory and SBB Strategy: Synthesis, Structure, and Adsorption Properties

Metal-organic frameworks (MOFs) with high porosity and good stability are a booming class of adsorbent materials exhibiting extensive gas adsorption and separation. In this work, a polyhedral heterometallic MOF, [InCu2(CBDA)(2)(H2O)(2)]center dot n(solvent) (In/Cu-CBDA) [CBDA = 5,5'-(carbonylbis(azanediyl))-diisophthalic acid], on the basis of tetracarboxylic ligand, has been successfully obtained by one-step synthesis. Based on the theory of hard and soft acid- base (HSAB), the formation of strong coordination bonds (high-valency In-carboxylate) results in excellent stability of In/CuCBDA when heated at 150 degrees C, exposured to the air, and soaked in the organic solvents. By utilizing a supermolecular building block (SBB) strategy, the coordination between isophthalate moieties and Cu(II) paddlewheels provides a platform for assembly of a metal-organic polyhedron (MOP), so that the In/Cu-CBDA displays permanent porosity and high adsorption selectivity of CO2/CH4,C2H6/CH4, and C3H8/CH4 as predicted by IAST. This work affords an idea to design and synthesize target MOF materials for broad possibilities in advanced applications through a combination of HSAB theory and SBB strategy.