Banca de DEFESA: SUELEN CATHERINE FARIAS PEREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : SUELEN CATHERINE FARIAS PEREIRA
DATE: 27/03/2023
TIME: 09:00
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

Complex [Eu(mppdOH)3]: from UV radiation dosimeter to molecular thermometer

KEY WORDS:

Europium. Luminescence. β-diketonate. Photo-oxidation. Photodegradation.

PAGES: 79
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

This work reports the synthesis, characterization, luminescent properties and photo-oxidation chemical reaction of the β-diketonate complex [Eu(mppd)3] (mppd = anion 1,3-Bis-(1-methyl-1H-pyrrol-2-yl) propan-1,3- dionate). In addition, we have investigated the preliminar UV dosimeter and molecular thermometer applications of its photo-oxidized form, [Eu(mppdOH)3]. Initially, the protonated ligand Hmppd (1,3-Bis-(1-methyl-1H-pyrrol-2-yl) propan-1,3-dione) was synthesized from the reaction between N-methylpyrrole and malonyl chloride. The Hmppd was characterized by 1H NMR, thermogravimetric analysis and gas chromatography-mass spectrometry. The complex [Eu(mppd)3] shows photoluminescence in the red region (5D0  7FJ, J = 0, 1, 2, 3 and 4) and undergoes photo-oxidation when exposed to UV radiation at 344 nm, resulting in the intensification of the luminescence of the Eu3+ ion. After 15 minutes of irradiation, the emission intensification reaches a plateau that is maintained for 10 minutes until it starts to fall. Attempts were made to produce luminescent devices by inserting the mppd ligand or the [Eu(mppd)3] complex in a supramolecular matrix of hydrogel and in a polymeric matrix of polyvinylpyrrolidone. However, these procedures have not produced satisfactory results. Furthermore, the photostability of the photo-oxidized complex, [Eu(mppdOH)3], under UV radiation exposure (λirr = 343 nm) was evaluated. The emission intensity had a loss of 80% after 60 minutes of exposure, evidencing its photodegradability. Moreover, the thermometric behavior of the [Eu(mppdOH)3] complex was investigated in the physiological temperature range, 303 to 323 K, using the ratio between the integrated emission intensities of the Eu3+ ion and the ligand (IEu/EiLig) as the thermometric parameter. The activation energy found by the Mott-Seitz model was 4,239 cm-1, assuming, therefore, that the Eu3+ charge transfer band is the main mechanism of luminescence deactivation. 

COMMITTEE MEMBERS:
Externo à Instituição - ADELMO SATURNINO DE SOUZA
Interna - 3218211 - MARCELLA AUXILIADORA DE MELO LUCENA
Presidente - 1354207 - SEVERINO ALVES JUNIOR