A stable mixed lanthanide metal-organic framework for highly sensitive thermometry.

A family of lanthanide-based MOFs (Ln-MOFs) with high thermal and chemical stability have been successfully synthesized by a solvothermal method. Owing to the intrinsic robustness of the framework and temperature-dependent luminescence behaviour of lanthanides, Eu3+/Tb3+-mixed MOFs ([(CH3)2NH2]Eu0.036Tb0.964BPTC) have also been successfully synthesized and targeted for developing excellent luminescent thermometers. The obtained mixed Ln-MOF exhibits ratiometric temperature sensing based on the distinguished characteristic emission of lanthanides with a wide temperature range from 77 K to 377 K. Particularly, the temperature sensor shows good linear responses from 220 K to 310 K with the maximum relative sensitivities (Sm) of 9.42% per K at 310 K. This value is comparable to those of the most excellent Ln-MOF thermometers reported. Besides, the temperature-dependent luminescent colours could also be systematically tuned from green, through yellow to red with increasing temperature, which can be clearly and directly observed even by the naked eye or a camera, thus also allowing colorimetric luminescence thermometry.