A stable 2D luminescent metal-organic framework as a highly sensitive sensor for Fe3+ and Cr2O72-/CrO42- in water

Reacting N,N '-bis(3,5-dicarboxyphenyl)oxalamide (H4BDPO) with d(10) electronic configuration Cd2+ ions under solvothermal conditions produces a two-dimensional (2D) metal-organic framework (MOF), {[Cd-3(HBDPO)(2)(H2O)(7)]center dot 4H(2)O}(n) (1), which has been further characterized by different methods, including X-ray single-crystal diffraction, elemental analysis, infrared (IR) spectroscopy, thermogravimetric (TG) analysis and powder X-ray diffraction (PXRD). The structural analyses of 1 indicate that two crystallographically independent Cd2+ ions are interconnected by partly deprotonated HBDPO3- ligands to generate a 2D (3,4)-connected topological layer, and the adjacent layers are further formed in a 3D supramolecular structure by hydrogen bonding and pi center dot center dot center dot pi stacking interactions. Luminescent results show that 1 can serve as a luminescent sensor for sensitively detecting Fe3+ and Cr2O72-/CrO42- ions based on the fluorescence quenching effect. More importantly, the high stability of 1 makes it suitable for the detection of Fe3+ and Cr2O72-/CrO42- ions in the natural water system.