Thiophene-functionalized heteronuclear uranium organic framework for selective detection and adsorption towards Mercury (II)

Mercury (II) metal ion is a headache problem due to its highly toxic and widely spread as an environmental pollutant. Herein, we design and synthesized a thiophene based heteronuclear uranyl organic framework {[Na(UO2)3(μ3-O)(μ2-OH)3(2,5-TDC)]•2H2O} (2,5-TDC ​= ​thiophene-2,5-dicarboxylic acid) (UOF1) for the selective sensing and adsorption towards Hg (II) in water. Among which, the regular 1D open channels and the accessible active soft base sulfur atoms arrayed on the pore walls play an important role for the Hg (II) grabbing and deposition, while the unique charge-transfer based “multi-peaks” fluorescent emission from the uranium centers act as the sensor towards the Hg (II). The detection limit and adsorption capacity are 2.488✕10−9 ​M and 244.32 ​mg ​g−1, respectively, which are among the top level performance for Hg (II) detection and remediation. In addition, density functional theory (DFT) calculations reveal that the Hg (II) affinity arising from the synergetic interactions of sulfur and oxygen supported by the UOF skeleton. This research demonstrates the dual functional utilization of a fluorescent MOF for both sensing and removal of metal ion, which highlights the facile construction of functionalized MOFs for heavy metals remediation.