An Ultrastable Metal–Organic Framework with Open Coordinated Sites Realizing Selective Separation toward Cationic Dyes in Aqueous Solution

Abstract

A novel Zn-based metal–organic framework (MOF) was synthesized from the mixed ligands, 3,3′,5,5′-azoxybenzenetetracarboxylic acid (H4AOBTC) and 1,4-bis(1H-benzo[d]imidazol-1-yl)benzene (phenDIB) ligand. The crystal structure of the complex exhibits an interpenetrated three-dimensional framework that can be simplified as a (4,4)-connected 2-nodal bbf net. This MOF displays extraordinary thermostability in boiling water for 12 h and chemical stability in a wide pH range of 2–13. The most intriguing feature is that it can successfully separate cationic dyes from mixed dye molecules in aqueous solution with high effectivity and selectivity, even for rhodamine B molecule with a large size. Furthermore, this material is reusable, and the adsorbed dye molecules can be released and recovered completely. It is very important for the practical application from a view of environmental protection and resource recycling.