A microporous anionic metal-organic framework for sensing luminescence of lanthanide(III) ions and selective absorption of dyes by ionic exchange.

Herein, a novel anionic framework with primitive centered cubic (pcu) topology, [(CH3 )2 NH2 ]4 [(Zn4 dttz6 )Zn3 ]⋅15 DMF⋅4.5 H2 O, (IFMC-2; H3 dttz=4,5-di(1H-tetrazol-5-yl)-2H-1,2,3-triazole) was solvothermally isolated. A new example of a tetranuclear zinc cluster {Zn4 dttz6 } served as a secondary building unit in IFMC-2. Furthermore, the metal cluster was connected by Zn(II) ions to give rise to a 3D open microporous structure. The lanthanide(III)-loaded metal-organic framework (MOF) materials Ln(3+) @IFMC-2, were successfully prepared by using ion-exchange experiments owing to the anionic framework of IFMC-2. Moreover, the emission spectra of the as-prepared Ln(3+) @IFMC-2 were investigated, and the results suggested that IFMC-2 could be utilized as a potential luminescent probe toward different Ln(3+) ions. Additionally, the absorption ability of IFMC-2 toward ionic dyes was also performed. Cationic dyes can be absorbed, but not neutral and anionic dyes, thus indicating that IFMC-2 exhibits selective absorption toward cationic dyes. Furthermore, the cationic dyes can be gradually released in the presence of NaCl.