Multifunctional luminescence properties of co-doped lanthanide metal organic frameworks

Two novel lanthanide metal organic frameworks [Eu4(bpt)4(DMF)2(H2O)6]·(DMF)5·(H2O)4 (1) and [Tb4(bpt)4(DMF)2(H2O)8]·(DMF)5·(H2O)3 (2) were synthesized under hydrothermal conditions, forming a three-dimensional structure (H3bpt = biphenyl-3,4′,5-tricarboxylate). Single crystal X-ray diffraction reveals that compounds 1 and 2 are heteromorphic and have different topologies due to the change of metal ions with different radii and coordination steric hindrance. The unique luminescence properties of Eu3+ and Tb3+ ions motivated us to dope different amounts of Tb3+ into a single host to obtain light tunable materials. The tunable multicolor emissions, including red, red-orange, orange, yellow and green, can be readily achieved from the doped Ln-MOFs 3–6 by increasing the concentration of Tb3+. In addition, compounds 5 and 6 also exhibit different temperature-dependent luminescence behaviors when the concentration of Eu3+ is low, generating new Ln-MOF thermometers.