Banca de QUALIFICAÇÃO: LÍVIA ELIAS DA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : LÍVIA ELIAS DA SILVA
DATE: 29/08/2025
TIME: 09:00
LOCAL: Google Meet
TITLE:

Synthesis and characterization of the TbBDC/CDs composite for application in luminescent thermometry.

KEY WORDS:

Carbon Dots; MOFs; lanthanides; luminescence; thermometry.

PAGES: 90
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

The development of luminescent temperature sensors (LTS) has sparked global efforts, as they offer multifunctionality, such as: imaging with spatial and temporal resolution, high sensitivity, and non-invasive measurement. In general, it is estimated that by 2034 the global market for temperature sensors will be valued at approximately US$ 20.96 billion, registering a CAGR of 7.20% between 2025-2034. In this scenario, Carbon Dots (CDs) and luminescent Metal-Organic Frameworks based on lanthanide ions
(Ln-MOFs) can be excellent candidates to act as LTS due to their potential applications in thermometry, such as in the fields of micro and nanoelectronics, micro and nanofluidics, the food industry, and medicine, among others. In this perspective, this work describes the synthesis and characterization of Ln-MOFs based on Tb³⁺ ions and the BDC²⁻ ligand (disodium benzene-1,4- dicarboxylate) (TbBDC), as well as its composite formed with Carbon Dots (TbBDC/CDs), for application in luminescent thermometry. Thus, the CDs were synthesized using red bell pepper as a precursor material, and HRTEM images revealed particles with a quasi-spherical morphology and an average size of 1.55 ± 0.39 nm. They also showed maximum fluorescence intensity at 448 nm, under λExc=360 nm. The TbBDC and TbBDC/CDs MOFs were prepared via ultrasound, mediated by
polyvinylpyrrolidone (PVP), with the in-situ incorporation of the CDs. As a result, the morphological and structural analyses of TbBDC and TbBDC/CDs revealed similar results, with both presenting flat and lamellar crystals and average sizes of 0.82 ± 0.25 and 0.81 ± 0.27 µm, respectively. On the other hand, the optical properties of TbBDC were improved with the incorporation of CDs, enabling the creation of a composite with a spectral distribution mainly in the blue and green regions. The thermometry tests of TbBDC/CDs demonstrated that the fluorescence intensity of the CDs (448 nm) progressively decreased with increasing
temperature, while that of the Tb³⁺ ions (5D4 → 7F5, 546 nm) remained constant. The coordinates on the CIE diagram varied from (0.23; 0.36) to (0.24; 0.41) at temperatures from 298 to 343 K. Furthermore, through the ratio of the fluorescence intensities (FIR=I 546 nm I 448 nm), a linear range was obtained from 298 to 343 K (R² = 0.99), with a maximum relative thermal sensitivity (Sr) of 1.62 % K⁻¹ at 298 K. Therefore, the material developed in this work shows promising results for application in luminescent thermometry, with a Sr greater than 1.00 % K⁻¹ and a wide detection range

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Presidente - 1869296 - CINTYA D'ANGELES DO ESPIRITO SANTO BARBOSA
Externo(a) à Instituição - FAUSTHON FRED DA SILVA - UFPB
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