A microporous shp-topology metal–organic framework with an unprecedented high-nuclearity Co10-cluster for iodine capture and histidine detection

Abstract

Herein we report the synthesis of a microporous shp-topology metal–organic framework (JNU-200) with 12-connected high-nuclearity Co₁₀-cluster and 4-connected carboxylate ligand, 4,4′,4′′,4′′′-(pyrazine-2,3,5,6-tetrayl)tetrabenzoate (BTTB). The redox potential of Co²⁺/Co³⁺ and the nitrogen-containing π-electron-rich BTTB render JNU-200 an ideal platform for iodine capture. Indeed, the adsorption capacity in iodine vapor can reach up to 1.08 g g⁻¹, comparable to the best-performing MOF materials reported so far. Kinetic studies show that JNU-200 can capture most of the I₂ from an iodine solution of 200 ppm within 48 h, corresponding to 99% removal efficiency, far exceeding many reported MOF materials. Single crystal X-ray diffraction was studied to reveal the structural changes of JNU-200 upon iodine adsorption and the precise location of the trapped iodine. Raman spectra analysis was performed to shed light on the host–guest interactions and the iodine adsorption mechanism. Furthermore, JNU-200 exhibits rapid and facile detection of histidine (His) with a luminescence turn-on response and a yellowish precipitate which was confirmed to be a mixture of cobalt complexes with His.