The mixed-ligand strategy to assemble a microporous anionic metal–organic framework: Ln3+ post-functionalization, sensors and selective adsorption of dyes

A unique microporous anionic metal–organic framework, namely [Zn2(btb)2(bbis)](Me2NH2)2·6DMF (1), has been synthesized and structurally characterized [bbis = bis(4-benzylimidazol-ylphenyl)sulfone and H3btb = 4,4′,4′′-benzene-1,3,5-triyltribenzoic acid]. This compound exhibits a 4-fold interpenetrated anionic framework with ins topology. The post-synthetic cation exchange of 1 with Eu3+, Tb3+, Dy3+ and Sm3+ afforded lanthanide(III)-loaded materials. Eu3+@1 and Tb3+@1 can be used as the potential luminescent probes in nitrobenzene. The adsorption behavior of 1 towards organic dyes was investigated, revealing rapid and selective separation of methylene blue.