Banca de DEFESA: DOUGLAS GOMES DA SILVA
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.STUDENT : DOUGLAS GOMES DA SILVA
DATE: 05/12/2023
TIME: 14:00
LOCAL: Auditório do Departamento de Química Fundamental
TITLE:
Effect of Symmetry Breaking by Inorganic Ligands in Europium Ternary Complexes: Synthesis and Luminescence.
KEY WORDS:
Luminescent Europium Complexes; Microwave Synthesis; β-Diketonate Ligands; Quantum Efficiency; Inorganic Ligands; Symmetry Breakers.
PAGES: 80
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:
The europium ternary complexes, coordinated with β-diketonate ligands, exhibit luminescent properties under ultraviolet radiation and find applications as luminescent thermometers, biological markers, and inorganic diodes. Highlighting the efficient synthetic routes, the Faster Synthesis method, developed at Lom, demonstrates high yields and reduced complex acquisition times. Advancing this methodology, the use of a microwave reactor results in a more sustainable approach with even shorter synthesis times and enhanced product purity. Our findings emphasize the crucial role of ligand addition order and the introduction of "symmetry-breaking" ligands in intensifying luminescence quantum efficiency. Current focus involves exploring luminescence properties with other symmetry-breaking ligands, adapting the Rapid Synthesis methodology to microwave reactors using different europium salts. In this dissertation, luminescent europium ternary complexes were synthesized in a microwave reactor with one or two symmetry-breaking ligands, with general formulas [EuX(β)2(L)2] and [EuX2(β)(L)3], where X = Cl- or NO3-, β = BTFA (4,4,4-trifluoro-1-phenylbutan-1,3-dionate) or TTA (4,4,4-trifluoro-1-thiophen-2-yl-butan-1,3-dionate), and L = TPPO (triphenylphosphine oxide) or PTSO (p-tolylsulfoxide). Our evaluation of Cl- and NO3- ligands' influence on complex structure, synthesis yields, and luminescence efficiency revealed generally higher yields with Cl- ligands, exemplified by [EuCl2(BTFA)(TPPO)3] and [Eu(NO3)2(BTFA)(TPPO)3] showing synthesis yields of 91% and 40%, respectively. Computational calculations of thermodynamic properties supported experimental results, indicating energetically favorable syntheses with Cl- ligands compared to NO3-. Luminescence property results highlighted the significant impact of the nitrate ligand on increased quantum efficiency, followed by the BTFA ligand in complexes such as [Eu(NO3)(BTFA)2(TPPO)2] (η = 57%), [Eu(NO3)2(BTFA)(TPPO)3] (η = 52%), [EuCl(BTFA)2(TPPO)2] (η = 51%), and [EuCl2(BTFA)(TPPO)3] (η = 49%). Conversely, the absence of nitrate or chloride led to lower quantum efficiency, as observed in the complex with three β-diketonates: [Eu(BTFA)3(TPPO)2] (η = 34%). These results indicate that inorganic ligands appear to disrupt the spherical symmetry of the complex, enhancing luminescence. Our study contributes to the development of simpler and more economical synthetic routes using microwave procedures and design strategies to enhance luminescence in europium complexes coordinated with β-diketonate ligands incorporating inorganic ligands.
COMMITTEE MEMBERS:
Externa ao Programa - 2174335 - IVANI MALVESTITI - nullPresidente - 1130509 - SIMONE MARIA DA CRUZ GONCALVES
Interna - 1283002 - YEDA MEDEIROS BASTOS DE ALMEIDA