Banca de QUALIFICAÇÃO: MIRIAM KEZIA NICOLAU GREGORIO DE OLIVEIRA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MIRIAM KEZIA NICOLAU GREGORIO DE OLIVEIRA
DATE: 13/02/2023
LOCAL: Laboratório 4 do PPG Ciência de Materiais
TITLE:

Effect of β-diketonates Diversification on Europium Complexes: Microwave Synthesis, Luminescence and Triboluminescence

KEY WORDS:

Microwave Synthesis. Europium complexes. β-diketonates. Emission quantum efficiency. Intensification. Triboluminescence.

PAGES: 153
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

Luminescent Europium complexes with β-diketonate ligands are widely studied due to their great importance from the point of view of fundamental chemistry and due to their wide range of applications. In this work, we apply and optimize methodologies using a microwave reactor instead of syntheses that employ conventional heating. The classes of europium complexes studied were tetrakis and mixed quaternaries (11 different complexes) and triskis and mixed ternaries (9 different complexes). The luminescent and triboluminescent properties of these complexes were studied. As a result of the microwave-assisted synthesis, we have significantly reduced the amount of solvent, reaction time and also, we improved reaction yields. Also, the complexes were obtained in crystalline form in a shorter lab bench time compared to the conventional method. All these factors contribute to demonstrate that the methodology using microwave reactor presented a greener chemistry. All complexes were characterized by IR and 1H and 19F NMR spectroscopy. 1H13C HSQC spectroscopy experiments were performed to support signal assignments. Luminescence spectroscopy (emission spectra, excitation spectra and lifetime curve) was mainly used to study the europium quaternary complexes: K[Eu(DBM)4], K[Eu(β)4], K[Eu(DBM)3(β)], K[Eu(DBM)2(β)2] and K[Eu(TTA)(BTFA)(DBM)(HFAC)] in which β ligands are HFAC, BTFA or TTA. The emission quantum efficiency data confirmed the conjecture of increased luminescence through the diversification of ligands in acetone and chloroform. For instance, in chloroform solution the average η of the tetrakis (31%) and quaternary complexes of mixed ligand (18% and 26%) were smaller than the η value for the complex with four different β (38%). The triboluminescent property was evidenced for the ternary complex [Eu(TTA)(BTFA)(DBM)(TPPO)2] through the detection of an emission spectrum when we rubbed its crystals. This complex had its property intensified through modifications in the conditions of microwave-assisted synthesis (MW2). This methodology was used to prepare the following triboluminescent complexes: [Eu(NO3)(TTA)2(TPPO)2], [Eu(TTA)3(TPPO)2], [Eu(HFAC)3(TPPO)2 ] and other three complexes which have not yet been known as triboluminescents [Eu(TFA)3(TPPO)2], [Eu(BTFA)3(TPPO)2] and [Eu(DBM)3(TPPO)2]. The synthetic method applying a microwave reactor and the presence of impurities contributed to reveal and intensify the triboluminescent activity of these complexes.

COMMITTEE MEMBERS:
Interna - 1857515 - GIOVANNIA ARAUJO DE LIMA PEREIRA
Interna - 3218211 - MARCELLA AUXILIADORA DE MELO LUCENA
Presidente - 1301548 - MARCELO NAVARRO