Luminescent terbium and europium probes for lifetime based sensing of temperature between 0 and 70 degrees C

Organic europium (III) and terbium (III) complexes (refered to as Eu1, Eu2, and Tb-L1, Tb-L2, respectively) have been synthesized that display bright emission and small bandwidth. Tb-L1 and TbL2 show lifetimes in the order of almost 1 ms at room temperature, good color purity, and high relative photoluminescence quantum yields. This makes them excellent probes for sensing temperature via measurement of luminescence lifetime. Probes Eu1, Eu2, Tb-L1 and Tb-L2 were incorporated into various polymer matrices to give sensor films for use as temperature-sensitive paints (TSPs). Eu (III) complexes have the advantage of being effectively excited by purple light-emitting diodes with their peak wavelengths of 405 nm. All TSPs based on these europium and terbium probes display good sensitivities to temperature, in particular, TSP based on Tb-L1 and Tb-L2 can show temperature lifetime sensitivities of -13.8 ms per degrees C and -9.2 ms per degrees C, respectively. Assuming a precision of +/- 1 ms in the determination of lifetime, this will enable temperature to be determined with a precision of around +/- 0.1 degrees C. This temperature dependence is the highest one reported so far for lanthanide complexes.