Two isostructural Ln-MOFs containing triazole groups as luminescent probes for efficient sensing of NACs and Fe3+

Two new isostructural 3D lanthanide metal–organic frameworks (Ln-MOFs), [Ln2(L)3(H2O)2]·2H2O·2DMF (1-Ln, Ln = Eu3+ and Tb3+, H2L = 5-triazole isophthalic acid) with uncoordinated triazole groups decorating the channels were successfully synthesized via solvothermal reaction. The uncoordinated triazole groups act as reserved host–guest binding sites to adjust the luminescence intensity of the Ln3+ ion. Luminescence studies reveal that 1-Eu and 1-Tb as fluorescent probes both exhibit high sensitivities and excellent selectivities towards nitroaromatics (NACs) and Fe3+ in DMF system by luminescence quenching process. The quenching mechanisms were investigated through PXRD, DFT theory calculation, XPS, UV–vis and discussed in details.