A water-stable europium-MOF sensor for the selective, sensitive ratiometric fluorescence detection of anthrax biomarker.

[Display omitted] • A three-dimensional Eu-MOF with excellent thermal and water stability is successfully synthesized. • The characteristic fluorescence of Eu3+ can be effectively restored by anthrax markers (DPA). • The ratiometric fluorescence sensor shows excellent sensitivity, outstanding selectivity, and superior accuracy for detection of anthrax markers. • Combined with density functional theory and a variety of other analytical methods, the detection mechanism of DPA by Eu-MOF is investigated in detail. Sensitive, efficient and rapid detection of 2, 6-pyridinedicarboxylic acid (DPA), commonly labeled as the main biology marker for bacillus anthracis, is of far-reaching consequence to eliminate potential threats. In this work, a 3D Eu-MOF ([Eu(DHBDC) 1.5 (DMF) 2 ·DMF) that has outstanding thermal and water stability was synthesized. The Eu-MOF showed characteristic fluorescence at 506 nm caused by ligand π-π* transition. The quantum calculation showed that there was a large energy difference between the 5D 0 level of Eu3+ and the triplet energy level of 2,5-dihydroxy terephthalic acid ligand (DHBDC2-), which was why the coordination compound did not exhibit the characteristic fluorescence of Eu3+. Interestingly, it effectively restored the red fluorescence of Eu3+ (593, 618 and 699 nm) and showed a dual-emission fluorescence response at 506 and 593 nm when the DPA existed. Therefore, based on the high detection sensitivity of Eu-MOF (the detection limit is 1.3 μM) and outstanding anti-interference ability, it is expected to become a prospective ratiometric fluorescence sensor for the detection of DPA. In addition, combined with density functional theory (DFT) and a variety of other analytical methods, the detection mechanism of DPA by Eu-MOF was investigated in detail. [ABSTRACT FROM AUTHOR]