Two luminescent lanthanide metal–organic frameworks as bifunctional fluorescent probes for Fe3+ and MnO4− ions

Two new Ln-MOFs, namely {[Ln(L)3]·DMF}n (Ln = Tb (1), Eu (2); HL = 4-pyridin-4-yl-benzoic acid), have been constructed by the reaction of HL, and Ln(OH)3 under solvothermal conditions. 1 and 2 are isomorphic and feature two-dimension frameworks with [Ln(COO)2]n chains. Notably, both 1 and 2 demonstrate high thermal stability and good luminescence. Furthermore, 1 and 2 can act as multi-responsive fluorescent probes for Fe3+ and MnO4− ions. The detection limits are 6.97, 7.06 and 2.77, 3.53 μM for 1 and 2, respectively, and the quenching constants (Ksv) are 8.01 × 103, 1.21 × 104 and 1.07 × 104, 1.43 × 104 M−1 for 1 and 2, respectively.