Tunable emission and selective luminescence sensing for nitro- pollutants and metal ions based on bifunctional lanthanide metal-organic frameworks

摘要

Series of Eu/Tb bifunctional metal-organic frameworks (MOFs) [EuxTb1-x(L)(H2O)(3)](n) (1-EuxTb1-x) (H4L+center dot Cl- = 1, 3-bis (3, 5-dicarboxyphenyl) imidazolium chloride) were synthesized successfully by solvothermal reaction. In these complexes, the adjacent Tb3+ or Eu3+ are linked by L3- to form two-dimensional sheet, and then forming three-dimensional framework by various H-bondings. All of complexes have wonderful selectivities and sensitivities for detecting 4-nitrophenol (4-NP) and Fe3+, comparatively speaking, the mixed [Eu0.5Tb0.5(L)(H2O)(3)] n (1-Eu0.5Tb0.5) has better sensing performance than isolate [Eu(L)(H2O)(3)] n (1-Eu) or [Tb(L)(H2O)(3)](n) (1-Tb) for 4-NP; while 1-Tb has better sensing performance for Fe3+, the highest quenching constants K-sv for 4-NP and Fe3+ reach to 7.5 x 10(6) M-1 and 9.6 x 10(5) M-1. The variable temperature XRD and regenerated experiments prove the good thermal and structural stabilities of 1-EuxTb1-x. Furthermore, the sensing mechanisms of complexes as bifunctional sensors have been explored in detail based on experiments and calculations.