Exploration of the Capacity of a Superstable Eu-MOF for Visualized Identification of 1-HP and Trp in Fresh Human Urine

1-Hydroxypyrene (1-HP) is known as the end product of polycyclic aromatic hydrocarbons (PAHs). Monitoring the content of 1-hydroxypyrene in human urine or serum can help measure the degree of polycyclic aromatic hydrocarbon poisoning in the human body. Tryptophan (Trp), one of the eight essential amino acids, plays a vital role in human growth and development. Therefore, exploration of a promising sensor for instant and accurate recognition of 1-HP and Trp has a profound influence on human health. Herein, a three-dimensional (3D) europium-centered metal–organic framework ([Eu(H2O)5]0.33[Eu(obdb)]·2DMF, Eu-MOF) with amazing air stability, acid–base stability, and thermal stability was constructed through the coordination interaction between Eu(III) ions and a V-typed semirigid ligand with two isophthalate groups (H4obdb, 4′,4‴-oxybis([1,1′-biphenyl]-3,5-dicarboxylic acid)) under a solvothermal condition. As expected, Eu-MOF can recognize 1-HP and Trp in binary solutions of DMF-H2O based on a significantly luminescent turn-off effect with high quenching efficiencies (99.2% for 1-HP and 93.8% for Trp), charming quenching constants (2.15 × 104 M–1 for 1-HP and 4.88 × 104 M–1 for Trp), low limit of detection (1.10 μM for 1-HP and 0.73 μM for Trp), and satisfactory antijamming capability. In addition, for detection of 1-HP or Trp, the color change of Eu-MOF from red to blue is visible to the naked eye as the concentration of 1-HP or Trp increases under a 365 nm UV lamp. Moreover, except in DMF-H2O solutions, the sensing capacities of Eu-MOF toward 1-HP and Trp are proven to be comparable in HEPES buffer solution and real samples.