Selective recognition of Hg ions in aqueous solution by a Cd-based metal-organic framework with good stability and vacant coordination sites.

A novel water-stable Cd-based metal-organic framework, namely {[Cd(BIBT)(TDC)]·2HO} (JXUST-28, BIBT = 4,7-bi(1-imidazol-1-yl)benzo-[2,1,3]thiadiazole and HTDC = 2,5-thiophenedicarboxylic acid), was synthesized using a mixed-ligand strategy. Structural analysis demonstrates that JXUST-28 exhibits a two-dimensional layer structure with 4-connected topology. Intriguingly, JXUST-28 presents good stability in boiling water (at least 5 days), common organic solvents and aqueous solutions with different pH values of 2-12 (more than 24 hours). Furthermore, fluorescence experiments revealed that JXUST-28 could sense Hg ions in aqueous solution a quenching effect with a detection limit of 0.097 μM. Meanwhile, JXUST-28 can also be regenerated at least 5 times to detect Hg ions. In addition, light-emitting diode lamps, luminescent films, and test papers of JXUST-28 have been successfully developed for practical applications.