Towards optic temperature sensor: luminescence of complexes with two emitting centers (Tb/Eu) and ligands based on 2,2’-bipyridyldicarboxylic acid
Kirill D. Shmelkov1, Anastasia V. Kharcheva1, Alexey V. Ivanov1, Natalia E. Borisova1, Svetlana V. Patsaeva1; 1Lomonosov Moscow State University, Moscow, Russia.
Abstract
The optical molecular thermometers with temperature-dependent emission properties (intensity, spectral bandshape or lifetime) are of great demand in multiple scientific fields. Luminescent lanthanide complexes are promising candidates for temperature sensing due to their unique spectroscopic properties: narrow spectral lines, long luminescence lifetimes and high emission intensities. In particular, mixed complexes of terbium and europium, thanks to their high temperature sensitivity and visible-wavelength luminescence, can be used to create ratiometric temperature sensors. The presence of two radiation centers allows to determine temperature based on relative rather than absolute parameters (ratiometric luminescence sensing). The purpose of this study is to investigate the temperature dependence of spectral luminescent characteristics of eight complexes containing ligands based on 2,2’-bipyridyldicarboxylic acid with two emitting centers (Tb and Eu) and similar complexes with only one emitting center (Tb). The absorption spectra, excitation and emission luminescence spectra were measured in the temperature range 298–328 K for solutions in acetonitrile. The luminescence lifetime and quantum yield of each emitting center, the ratio of luminescence intensities of Tb and Eu were calculated and their temperature dependences were obtained. It was found that absorption spectra are almost unaffected by temperature. The effect of temperature on luminescence of each ion, as well as the effect of simultaneous presence of two emitting centers in the mixed solution are described. We found that the terbium luminescence intensity decreased reversibly with rising temperature and increased with decreasing temperature, while the opposite effect was observed for europium in some mixed complexes. This research was funded by Russian Science Foundation, grant number 23-22-00103
https://rscf.ru/project/23-22-00103/.
Speaker
Kirill
Faculty of Physics, Lomonosov Moscow State University, Russia
Russia
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