Europium(III)/Terbium(III) mixed metal-organic frameworks and their application as a ratiometric thermometer

The ability to molecularly engineer luminescent metal-organic frameworks is a powerful tool for the design of better performing rational temperature sensors. Lanthanide based MOF stand out as luminescent temperature sensors due to the high luminescence intensity and sharp emission lines of the lanthanides. The use of two different lanthanide cations incorporated into the same MOF structure is supposed to allow for a rational, that is self-referencing, temperature sensing. Here, we present series of mixed EuxTb(1-x)BTC, which were designed as nanoparticles. The EuxTb(1-x)BTC series shows controllable luminescent properties, which depend on the solvation of the lanthanide. The two MOFs in the series with the lowest Eu content, i.e. Eu0.04Tb0.96BTC and Eu0.02Tb0.98BTC, are suitable candidates for rational temperature sensing in the range between 200 and 270 K and above 300 K.