A Eu and Tb co-doped MOF-5 compound for ratiometric high temperature sensing

In this work, a new Eu and Tb co-doped luminescent compound based on MOF-5, [Zn₄O(BDC)₃], (named as compound 1) was successfully synthesized. The structure and morphology characterizations demonstrate that the initial framework of MOF-5 is retained well after co-doping Eu and Tb. The systematic investigations of photoluminescence behaviors reveal that the heat-treated compound 1 (called as compound 1a) can be utilized as a multi-channel readout luminescent thermometer in emission intensity ratio, decay time ratio, and luminescence color. It simultaneously exhibits the excellent repetitiveness and reversibility under high temperature region from 303 to 473 K. The relative sensitivity of 1.8%/K at 473 K is much higher than the best one of 1.19%/K previously reported for the mixed-lanthanide MOF Tb_0.8Eu_0.2BPDA. Until now, such a ratiometric luminescent thermometer with a high sensitivity at the temperature as high as 473 K has been rarely explored.