A quantitative ratiometric fluorescent Hddb-based MOF sensor and its on-site detection of the anthrax biomarker 2,6-dipicolinic acid

Hydrothermal reactions of 1,3-di(3 ',5 '-dicarboxylphenyl)benzene (H(4)ddb) with Eu3+ and Tb3+ produced a series of hetero metal-organic frameworks (TbxEu1-x-Hddb). The optimized Tb0.875Eu0.125-Hddb showed high stability in organic solvents, HEPES buffer solution, NaOH and HCl solutions with pH = 2-11. TbxEu1-x-Hddb exhibited the combined characteristic transitions of Eu3+ (D-5(0) -> F-7(J) (J = 1-4)) and Tb3+ (D-5(4) -> F-7(J) (J = 6-3)). The sensitivity test of Tb0.875Eu0.125-Hddb revealed a linear response of I-545/I-613 = 0.0362 center dot C-DPA + 0.3176 with a LOD of 0.8494 mu M, and seven interferents did not influence its detection performances. The paper-based MOF sensor Tb0.875Eu0.125-Hddb displayed obvious emission color conversions at C-DPA = 60 mu M, and a linear equation of G/R = 0.01091 center dot C-DPA + 0.12092 with a LOD of 19.1 mu M by recognizing the RGB values of the paper-based MOF, showing a prospect for a rough on-site DPA detection. Tb0.875Eu0.125-Hddb and its paper-based sensor are quantitative ratiometric fluorescent sensors for DPA detection with high sensitivity and selectivity, and rapid response and convenience.