A series of europium-based metal organic frameworks with tuned intrinsic luminescence properties and detection capacities

Three new isostructural luminescent complexes [(CH3)2NH2]2[Eu6(μ3-OH)8(BDC-NH2)6(H2O)6], [(CH3)2NH2]2[Eu6(μ3-OH)8(BDC-F)6(H2O)6] and [(CH3)2NH2]2[Eu6(μ3-OH)8(BDC-NO2)6(H2O)6] have been synthesized based on [(CH3)2NH2]2[Eu6(μ3-OH)8(1,4-NDC)6(H2O)6] under solvothermal conditions. In addition, these Eu-MOFs possess tuned intrinsic luminescence properties and detection capacities for different analytes, such as Cr2O72−, acetone and Fe3+. Here, these Eu-MOFs display distinct intrinsic luminescence properties because of the synergistic effect of donor groups and nonradiative vibrations, which are reflected in the lifetime, fluorescence quantum yield and emission intensity. Meanwhile, the detection experiments show that the one with the higher fluorescence quantum yield displays much more sensitive and efficient detection capacities for different kinds of analytes. Overall, this work indicated that tuning functional groups is vital to gain Eu-MOFs with good intrinsic luminescence properties, and make the detection capacities more sensitive and efficient.