Efficient adsorption of organic dyes by two porous heterometallic metal–organic frameworks assembled with Schiff base ligands and Fe3+/Cd2+ ions

Abstract Two porous heterometallic metal–organic frameworks (HMOFs), [Cd 2 (Fe-L1) 2 (µ 2 -O)(H 2 O) 2 ]·4DMF·MeOH·2H 2 O ( 1 ), and [Cd 2 (Fe-L2) 2 (µ 2 -O)(H 2 O) 2 ]·3DMF ( 2 ) (H 4 L1 =  N,N ′-cyclohexanediaminebis-(2-hydroxyl-6-carboxy-1-naphthaldehy) and H 4 L2 =  N,N ′-o-phenylenediaminebis-(2-hydroxyl-6-carboxy-1-naphthaldehy) have been synthesized and characterized under solvothermal conditions. Both HMOFs feature porous 3D frameworks constructed from square-pyramidal coordinated Fe 3+ ions, [Cd 4 (COO) 8 (H 2 O) 4 ] tetranucler clusters and Schiff base anions. However, 1 and 2 have different cavities because of the different coordination modes and spatial orientations of L1 4− and L2 4− anions. The adsorption performance of 1 and 2 towards eight organic dyes in aqueous solutions had been investigated. The result shows that 1 exhibits better adsorption ability than 2 .