Structural diversity of six metal–organic frameworks from a rigid bisimidazole ligand and their adsorption of organic dyes

Abstract

Six metal–organic frameworks, namely, [Cd₂(odc)₂(2,6-bin)₂]·(CH₃)₂NH (1), [Cd₂(tdc)₂(2,6-bin)₂(H₂O)₂] (2), [Cd₂(bzdc)₂(2,6-bin)₂]·4DMF (3), [Cd₂(hfdc)₂(2,6-bin)₂]·H₂O (4), [Cd₃(tpo)₂(2,6-bin)₃(H₂O)₄]·2DMF·2H₂O (5) and [Zn₃(btb)₂(2,6-bin)]·8DMF (6) {2,6-bin = 2,6-bisimidazoylnaphthalene, H₂odc = 4,4′-oxybisbenzoic acid, H₂tdc = thiophene-2,5-dicarboxyl acid, H₂bzdc = benzophenone-4,4′-dicarboxylic acid, H₂hfdc = 2,2′-bis(4-carboxyphenyl)hexafluoropropane, H₃tpo = tris-(4-carboxylphenyl)phosphine oxide and H₃btb = 4,4′,4′′-benzene-1,3,5-triyl-tribenzoic acid} have been synthesized and structurally characterized. Compound 1 exhibits a three-fold interpenetration of 4T25 network. Compound 2 presents a five-fold interpenetration of dia network. Compound 3 displays a 2D → 2D three-fold interpenetration of sql layers. Compound 4 features a 2D → 3D parallel polycatenation of sql layers. Compound 5 exhibits an unusual 3,4,6-connected self-catenated network of 3,4,6T206 topology. Compound 6 shows a rare 3,8-connected self-catenated network of 3,8T72 topology. Their adsorption behaviors to organic dyes have been studied.