Water-Stable Metal-Organic Frameworks for Fast and High Dichromate Trapping via Single-Crystal-to-Single-Crystal Ion Exchange

Two metal-organic frameworks [Zn-2(Tipa)(2)(OH)] center dot 3NO(3)center dot 12H(2)O (FIR-53, FIR denotes Fujian Institute of Research, Tipa = tris(4-(1H-imidazol-1-yl)phenyl)amine)) and [Zn(Tipa)] center dot 2NO(3) center dot DMF center dot 4H(2)O) (FIR-54) with large nanotubular channels were synthesized via Zn(II) ions coordinate the neutral Tipa ligand. The framework of FIR-53 contains 1D channels along the c axis with a cross section of 18 x 13 angstrom(2). FIR-54 also consists of large channels with the 10.5 x 10.5 angstrom(2) open windows. These porous materials efficiently trap Cr(2)O7 (-)(2) inorganic pollutant ions via the single-crystal-to-single-crystal (SC-SC) approach. The Cr2O7 (2-) uptake capacities of FIR-53 and FIR-54 are high to 74.2 and 103 mg/g, respectively. Furthermore, the Cr2O7 (2-) trapping-releasing process of FIR-53 displays good regeneration. Meaningfully, the structure of FIR-53 after ion exchange can be accurately obtained by single-crystal X-ray diffraction, which further elaborates the SC-SC transformation.