A rare (3,12)-connected zirconium metal-organic framework with efficient iodine adsorption capacity and pH sensing

We report here a stable rare zirconium metal-organic framework (MOF) exhibiting a sky topology, Zr-6(mu(3)-O)(4)(mu(3)-OH)(4)(ITTC)(4) (UPC-158) (where H3ITTC = 4,4',4 ''-(1H-imidazole-2,4,5-triyl)tribenzoic acid), established by Zr-6(mu(3)-O)(4)(mu(3)-OH)(4)(-COO)(12) clusters and 4,4',4 ''-(1H-imidazole-2,4,5-triyl)tribenzoic acid with abundant pi-electrons as an ideal material for removing iodine vapor - a major radioactive fission waste. The iodine adsorption efficiency of the acid-treated UPC-158-HX series shows a substantial improvement compared with that of the parental UPC-158 (1.77 g g(-1)), and the iodine vapor uptake of 2.92 g g(-1) at 343.15 K for UPC-158-HCl has reached the maximum value among the reported MOF materials. In addition, the protonation and deprotonation of imidazole nitrogen alter the symmetry of internal structures, resulting in a strong fluorescence enhancement of the material in the pH range of 10-11, making it a potentially precise pH meter. This work not only provides insights into the discovery of unprecedented structures and topologies through the rational choice of organic linkers via experimental and simulation methods but also paves the way to understand the structure related functional applications. It also opens up a window for the design and construction of highly complex porous and stable structures for sophisticated applications.