Logo de 22nd International Symposium on Bioluminescence and Chemiluminescence & 20th International Symposium on Luminescence Spectroscopy
Wait a moment for the page to load

Enter your credentials

Fechar janela

Sign up

Forgot your password?

Logo 22nd ISBC & 20th ISLS
MENU

Abstracts

Luminescent materials for imaging, sensors and theranostics

Employing an iridiumIII complex in luminescent thermometry: a multiparametric thermal sensing and multiple regression approach

Renan C. Silva1, Ana M. Pires1, Rute A. S. Ferreira2, Luís D. Carlos3, Sergio. A. M. Lima1

1São Paulo State University (Unesp), School of Technology and Sciences, Presidente Prudente, SP, Brazil, 2University of Aveiro (UA), CICECO, Institute of Materials, Aveiro, 3810-193, Portugal , 3University of Aveiro (UA), CICECO, Institute of Materials, Aveiro, 3810-193, Portugal

E-mail: renan.caike@unesp.br

In the past decade, luminescence thermometry has made significant advancements, approaching current measurement technologies. Typically, a thermometer performance is evaluated based on the relative thermal sensitivity (Sr) and temperature uncertainty (dT). Some thermometric parameters (∆) of a single emitting center can be explored and combined, such as emission intensity, spectral positions of absorption and emission bands, emission bandwidth, anisotropy, luminescence decay time, and relative intensity between two emission bands (ratiometric systems). However, in the literature there are few works that explores thermometry in IrIII complexes. In IrIII complexes, the emission comes from the 3LC-1,3MLCT hybrid state, with triplet 3MLCT being dominant at high temperatures. This emission experiences strong temperature dependence due to the rigidochromic effect. Therefore, we report the synthesis of an IrIII-complex and thermometry studies based on the performance of a multiparametric luminescent thermometer. To make this possible, the synthesis consisted of the preparation of a μ-chlorobridged cyclometalated IrIII dimer [Ir(Fppy)2(μ-Cl)2Ir(Fppy)2], followed by the insertion of the ancillary ligand pdc to form the heteroleptic complex [Ir(Fppy)2pdc], where Fppy = 2-(2,4-difluorophenyl) and pdc = 2,4-pyridinedicarboxylic acid, resulting in a yellow solution with a strong green emission under UV irradiation. After slow evaporation of solvents, the crude product was purified by column chromatography with silica gel. The complex [Ir(Fppy)2pdc] was obtained as a yellow powder. Yield: 87%. Quantum yield (ΦDMSO solution): 47%. The emission spectrum of the complex [Ir(Fppy)2pdc] (lmax = 553 nm) at RT, exhibited a broadened band with an unstructured profile, indicating a greater 3MLCT character. Emission spectra were acquired varying the temperature from 11 to 320 K, revealing spectral changes as the temperature decreased. At lower temperatures, bands appeared at 485 nm and 513 nm, attributed to the emission of 3LC vibronic splittings, which exhibit practically invariable energies with increasing rigidity. However, it is notable that the 3MLCT band is strongly influenced by temperature, with the rigidochromic effect destabilizing it, resulting in a shift to lower energies as the temperature increases. The thermally coupled nature of the 3LC/3MLCT levels enabled us to utilize the ratiometric approach, resulting in a maximum Sr of 1.25% K-1 within the 11 – 125 K temperature range. By using the 3MLCT band shift parameter (18507 – 17410 cm-1), it was possible to obtain a maximum Sr of 0.033% K-1 in all temperature range. Finally, using the lifetime ∆, a high sensitivity of 4.40% K-1 (11 – 125 K) was found. Thus, these results place the multiparametric approach using the luminescence of IrIII complexes at the center of attention in luminescence thermometry, demonstrating new paths for thermometry.

Keywords: Luminescence thermometry, Ir(III) complexes, ratiometric approach, multiparametric luminescent thermometer

Acknowledgments: Thanks to FAPESP for scholarship (2022/14042-6).


Search for submitted abstracts

You can select one or more search filters