Europium(III)-Doped Gadolinium(III) Complex for High-Sensitivity Temperature Sensing in the Physiological Range.

A new Eu 3+ -doped Gd 3+ complex of formula [Eu 0.0135 Gd 0.9865 (pta) 3 me-phen] was synthesized and structurally characterized (Hpta = benzoyltrifluoroacetone, me-phen = 5-methyl-1,10-phenanthroline). The photoluminescence study revealed that when the compound was excited at RT, under a 457 nm continuous laser, the material exhibited high luminescence due to the antenna effect of the ligands, as well as a good balance between the phosphorescence from the spin-forbidden triplet (from the organic ligands), and the characteristic lanthanide f-f transitions. The ratio between the previous emissions drastically changed when the sample was heated up to 62 °C inside a tubular furnace. This ratio was investigated using the luminescence intensity ratio method, to analyze the capabilities of the sample as a temperature sensor. The relative sensitivity reached a maximum of 11.4 °C -1 %, maintaining a detection limit below 0.15 °C for the whole temperature range.