Enhancement of Thermal Sensitivity of MOF-5 Doped with Eu3+ and Addition of Mn2+

This work investigates the potential of Eu3+ and Eu3+-Mn2+ doped metal-organic frameworks (MOFs) of the MOF-5 type as a temperature sensor (298-393 K). The MOF-5 were synthesized via reflux and characterized using X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and spectroscopic techniques. The emission spectra of the MOFs were obtained in response to temperature variations to define the thermometric configurations and sensor performance. The MOF-5 containing only Eu3+ showed low thermal sensitivity in the temperature range between 298-393 K, with a maximum sensitivity of 0.12% K-1. In turn, the addition of Mn2+ to MOF-5 (MnEu-MOF-5) was examined in a specific increase in thermal sensitivity close to 8% K-1 estimated at the temperature of 303 K. Computational calculations were important for the structural elucidation of MOF-5 with Eu3+ and understanding the energy transfer processes involved. The results show that the incorporation of Mn2+ into EuMOF-5 may be a promising candidate for application as a luminescent thermometer, since it presented high sensitivity for temperature measurement close to 303 K.