Eu3+-postdoped MOFs are used for fluorescence sensing of TNP, TC and pesticides and for anti-counterfeiting ink application.

Two europium-postdoped metal organic frameworks (MOFs) Eu3+@1 and Eu3+@2 [ 1 :{[Zn 2 (bta)(bpy)(H 2 O) 2 ]·2H 2 O} n , 2 :{[Ni(bta)(bpy)(H 2 O) 2 ][Ni(bpy)·(H 2 O) 4 ]·4H 2 O} n (H 4 bta = 1, 2, 3, 5-benzenetetracarboxylic acid, bpy = 4, 4′-dipyridine)] were prepared by hydrothermal synthesis and post-synthesis modification. MOFs 1 – 2 are all three-dimensional network structure connected by (bta)4- and bpy ligands. Eu3+@ 1 and Eu3+@ 2 in aqueous solution can achieve the quantitative detection of 2, 4, 6-trinitrobenzene (TNP), tetracycline (TC) and pesticides with high sensitivity and selectivity. In particular, when the volume of TNP increases to 50 μL, the luminescence quenching rate of Eu3+@ 2 can reach 99.7% and the LOD for TNP can reach 78 nM. Interestingly, Eu3+@1 has a good response to PTH (Pyrimethanil), while Eu3+@ 2 has a good selectivity to FLU (Fluazinam), and both can be used for rapid in-situ imaging detection of simulated pesticide residues on fresh vegetables. Under UV lamp, Eu3+@ 1 showed a significant fluorescence quenching effect on PTH in beans, while the fluorescence quenching effect of Eu3+@ 2 on FLU on cabbage was obvious. Surprisingly, two kinds of composite materials can be used as anti-counterfeiting ink functional material with strong anti-counterfeiting ability and long term stability. Two kinds of fluorescence sensors (Eu3+@ 1 and Eu3+@ 2) were synthesized by post-synthetic modification method. The sensor not only has high sensitivity, selectivity, stability and anti-interference ability to TNP, TC, PTH/FLU, but also can effectively detect pesticides on vegetables. It is particularly meaningful that they can be used as anti-counterfeiting ink. [Display omitted] • Two Eu-postdoped MOFs Eu3+@ 1 and Eu3+@ 2 were obtained by post-synthesis. • Eu3+@ 1 and Eu3+@ 2 sensors can achieve the quantitative detection of TNP, TC and pesticides with high sensitivity and selectivity. • Eu3+@ 1 has a good response to PTH, while Eu3+@ 2 has a good selectivity to FLU. • Eu3+@ 1 and Eu3+@ 2 have significant fluorescence quenching effect on PTH in bean and FLU in cabbage, respectively. • They can be used as anti-counterfeiting ink with strong anti-counterfeiting ability and long term stability. [ABSTRACT FROM AUTHOR]