Preparation of Eu(0.075)Tb(0.925)-Metal Organic Framework as a Fluorescent Probe and Application in the Detection of Fe(3+) and Cr(2)O(7)(2−)

Luminescent Ln-MOFs (Eu(0.075)Tb(0.925)-MOF) were successfully synthesised through the solvothermal reaction of Tb(NO(3))(3)·6H(2)O, Eu(NO(3))(3)·6H(2)O, and the ligand pyromellitic acid. The product was characterised by X-ray diffraction (XRD), TG analysis, EM, X-ray photoelectron spectroscopy (XPS), and luminescence properties, and results show that the synthesised material Eu(0.075)Tb(0.925)-MOF has a selective ratio-based fluorescence response to Fe(3+) or Cr(2)O(7)(2−). On the basis of the internal filtering effect, the fluorescence detection experiment shows that as the concentration of Fe(3+) or Cr(2)O(7)(2−) increases, the intensity of the characteristic emission peak at 544 nm of Tb(3+) decreases, and the intensity of the characteristic emission peak at 653 nm of Eu(3+) increases in Eu(0.075)Tb(0.925)-MOF. The fluorescence intensity ratio (I(653)/I(544)) has a good linear relationship with the target concentration. The detection linear range for Fe(3+) or Cr(2)O(7)(2−) is 10–100 μM/L, and the detection limits are 2.71 × 10(−7) and 8.72 × 10(−7) M, respectively. Compared with the sensor material with a single fluorescence emission, the synthesised material has a higher anti-interference ability. The synthesised Eu(0.075)Tb(0.925)-MOF can be used as a highly selective and recyclable sensing material for Fe(3+) or Cr(2)O(7)(2−). This material should be an excellent candidate for multifunctional sensors.