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

Abstract

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 Eu_xTb_1−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-Eu_xTb_1−x and the tri-metallic doped 1-Eu_0.01Gd_0.6015Tb_0.3885 with white light emitting MOFs were fabricated by doping diverse concentrations of Eu³⁺, Tb³⁺ and Gd³⁺ ions. More interestingly, 1-Eu_0.01Gd_0.6015Tb_0.3885 has a higher quantum yield (36.49%). Meanwhile, 1-Ln shows excellent performance in fluorescence sensing (K_sv = 1.5143 × 10⁴ M⁻¹) and anticounterfeiting applications.