Luminescence modulation, near white light emission, selective luminescence sensing, and anticounterfeiting via a series of Ln-MOFs with a π-conjugated and uncoordinated lewis basic triazolyl ligand

A new series of isomorphic lanthanide metal–organic frameworks (Ln-MOFs), {[Ln2(L)3·DMF·H2O]·DMF·H2O}n (denoted as 1-Ln, Ln = Eu, Gd, Tb or EuxTb1−x), were constructed using the 4′-(1H-1,2,4-triazol-1-yl)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H2L) ligand and Ln3+ ions under solvothermal conditions. 1-Ln shows a binodal (3,3,8)-connected three-dimensional (3D) framework based on a π-conjugated and uncoordinated Lewis basic triazolyl ligand. Then, six two-color doped 1-EuxTb1−x and the tri-metallic doped 1-Eu0.01Gd0.6015Tb0.3885 with white light emitting MOFs were fabricated by doping diverse concentrations of Eu3+, Tb3+ and Gd3+ ions. More interestingly, 1-Eu0.01Gd0.6015Tb0.3885 has a higher quantum yield (36.49%). Meanwhile, 1-Ln shows excellent performance in fluorescence sensing (Ksv = 1.5143 × 104 M−1) and anticounterfeiting applications.