Design of new europium-doped luminescent MOFs for UV radiation dosimetric sensing

We have reported the use of luminescent metal-organic frameworks for the development of a new alternative for UV-B radiation sensing. For obtaining the sensor, a doping sequence of Europium (1%, 2%, and 5%) was performed on the Zn(BDC)(dpNDI)(DMF) using solvothermal synthesis. The final material was characterized using powder X-ray diffraction (PXRD), Infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and spectroscopic investigation. The sensing phenomenon was studied from the controlled exposure of the Zn(BDC)(dpNDI):2% Eu coordinating polymer (without DMF in the structure) under UV-B radiation. Analysis of PXRD revealed that materials Zn(BDC)(dpNDI)(DMF): x% Eu (x = 1, 2 and 5%) show maintenance of the original MOF structure after incorporation of Eu3+ ion. The results of FT-IR indicate that Europium is connected in the compound by coordination bonds, evidenced by a detailed analysis of the symmetrical and asymmetric stretching of the ligand carbonyl group. The spectroscopic analysis for the material assisted in the realization of the correlation between the proposed structure and the environment occupied by the lanthanide ion. The sensing properties were studied for the compound Zn(BDC)(dpNDI):2%Eu mainly by the evaluation of the emission spectrum. The compound showed a significant decrease in its emission intensity after exposure to the UV-B radiation dose (0-9 J.cm-2), a phenomenon that has been explored in the composition of the sensor. The sensing mechanism was estimated through the analysis of ultraviolet-visible absorption spectrum and reflectance spectra in the determination of its direct and indirect band gap. Finally, the compound Zn(BDC)(dpNDI):2%Eu presented a versatile material for the development of tunable emitter material (exhibiting white light emission) and a promising dosimetric sensor of UV radiation light.