Terbium-europium fluorides surface modified with benzoate and terephthalate anions for temperature sensing: Does sensitivity depend on the ligand?

Abstract Synthesis, morphology investigation and the study of luminescent properties temperature dependence of surface modified bimetallic europium-terbium fluorides (L@Tb x Eu 1-x F 3 , L = benzoate or terephthalate anion), as well as their use in bioimaging is described. It was shown that the synthetic route and the solvent affects the Tb x Eu 1-x F 3 nanoparticle morphology. Moreover, the oriented attachment of Tb 0.999 Eu 0.001 F 3 crystallites was observed for the first time. Luminescence intensity of nanoparticle surface modified with aromatic carboxylate anions significantly increased, depending on the ligand used, while the temperature sensitivity of Tb x Eu 1-x F 3 was only slightly affected by the organic ligand. The examination of L@Tb 0.999 Eu 0.001 F 3 temperature dependence revealed excellent linearity both in low temperature range (77–293 K) and in physiological range (305–330 K) with temperature sensitivity of 0.4% K −1 at 40 °C. According to in cellulo tests, tph@Tb 0.999 Eu 0.001 F 3 demonstrated uniform distribution in cell cytoplasm and exhibited intense ionic luminescence of both terbium and europium.