A highly sensitive luminescent metal-organic framework thermometer for physiological temperature sensing

Thermal sensing and imaging in the physiological temperature range are of great importance for studying physiological processes and treating diseases. Metal-organic frameworks (MOFs) exhibit great promise for developing luminescent thermometers due to their remarkable structural diversities and tunable luminescence properties. Here, we synthesized a series of luminescent mixed-lanthanide MOFs, Eu(x)Tbi(1-x),BPT (x = 0.019, 0.058, 0.106; H3BPT = biphenyl-3,4',5-tricarboxylate acid) and adopted powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) to characterize the resulting products. The temperature-dependent photoluminescence emission spectra were recorded to investigate their potential applications in physiological temperature readout. It is found that the intensity ratio of Tb3+ to Eu3+ is linearly correlated with temperature and the relative sensitivity is higher than 1.5%/degrees C over the entire physiological temperature range. Furthermore, the temperature-dependent luminescence color emission allows for visual colorimetric temperature measurements. Luminescence lifetime testing and triplet energy level measurement were further conducted to study the mechanism. (C) 2018 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.