Investigação teórica de complexos luminescentes de eu3+: elucidação dos mecanismos de transferência de energia e desenvolvimento de um protocolo computacional para predição do rendimento quântico

Abstract

This work aimed to theoretically investigate the luminescent propertiesof Eu3+complexes containing β-diketonate ligands, focusing on understandingtheenergytransfer and backtransfer mechanisms responsible for the luminescent efficiencyofthese systems. Using semi-empirical methodologies, four complexes withpotential technological applications were studied: [Eu(tta)3(5,5’-dmbpy)] and [Eu(btfa)3(5,5’-dmbpy)], applied in the construction of OLED devices, and [Eu(tta)3(δ-val)(H2O)] and[Eu(btfa)3(δ-val)(H2O)], investigated as luminescent markers for gunshot residue.The theoretical investigation of these systems was necessary to understand, at themicroscopic scale, the photophysical processes that govern the luminescentperformance of the complexes, allowing them to be correlated withtheoptical properties observed experimentally. The theoretical results obtained agreedwell withthe experimental data provided by collaborators, demonstrating that thecalculatedproperties consistently describe the luminescent behavior of the studiedcompoundsand explain their efficiency in different technological applications. Inadditiontophotophysical studies, this thesis also involved the development of anewcomputational protocol for predicting the quantum yield in Eu 3+ complexes. Themodel was parameterized and validated using experimental quantumyield dataavailableinthe literature for a library composed of 17 Eu 3+ complexes. The results demonstratedhigh accuracy in reproducing the experimental quantum yields, presentingameanabsolute error of around 10%, a value significantly lower than those observedfortheanalytical models traditionally employed in the literature, whose mean errorsrangedbetween approximately 20% and 55%. Thus, this work contributes to theelucidationof the photophysical mechanisms of Eu 3+ complexes and presentsanewcomputational methodology for the precise prediction of quantumyield.