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Previous issue date: 2017-01-26 / CNPQ / Metodologias te´oricas s˜ao ´uteis para complementar investigac¸˜oes experimentais e guiar novos
experimentos envolvendo compostos luminescentes de lantan´ıdeos. A ausˆencia de uma ferramenta
computacional contendo tais m´etodos motivou o desenvolvimento do LUMPAC. Se por
um lado o LUMPAC difundiu o uso dessas metodologias, por outro as suas limitac¸˜oes tamb´em
foram evidenciadas. Nesse sentido, pˆode-se conhecer melhor quais m´etodos merecem uma
atenc¸˜ao especial, a saber: c´alculo dos parˆametros de intensidade (Ωλ), c´alculo da energia dos
estados excitados dos ligantes e c´alculo da taxa de emiss˜ao n˜ao-radiativa (Anrad). O objetivo
geral do presente trabalho de doutoramento consiste em corrigir algumas dessas limitac¸˜oes.
Quantoaoc´alculodosΩλ,conseguimosatenuaroproblemacomumanovaformadeajustedos
fatores de carga e das polarizabilidades atrav´es de um procedimento que foi denominado de
Modelo da UnicidadeQDC, o qual faz uso de um conjunto bastante reduzido de parˆametros
(Q,D eC). A importˆancia do ajusteQDC ´e que todas as quantidades derivadas se tornam
tamb´em ´unicas para uma dada geometria do complexo, incluindo um esquema proposto de
partic¸˜ao qu´ımico da taxa de emiss˜ao radiativa (Arad) em termos dos efeitos dos ligantes. Para
demonstrar uma das poss´ıveis aplicac¸˜oes dessa partic¸˜ao, foi considerado o caso de complexos
tern´arios de Eu3+ de ligantes n˜ao-iˆonicos repetidos e com os ligantes betadicetonatos DBM,
TTA e BTFA. A partic¸˜ao ordenou perfeitamente a combinac¸˜ao n˜ao ´obvia de pares de ligantes
n˜ao-iˆonicos que levam aos compostos misturados com os maiores valores deAexp
rad. Quanto
ao c´alculo dos estados excitados dos ligantes, ´e proposta uma parametrizac¸˜ao do m´etodo CIS
baseadonaaproximac¸˜aoNDDO,exclusivamenteparasistemaslantan´ıdicos. Al´emdisso,realizamosumestudoavaliativodemetodologiasTDDFTaplicadasaoc´alculodeestadosexcitados
de ligantes em complexos de lantan´ıdeos. Dentre os funcionais e func¸˜oes de base avaliados, a
combinac¸˜ao LC-ωPBE/6-31G(d) foi aquela que forneceu as energias tripleto mais concordantes
com os dados obtidos na literatura, sendo o erro m´edio absoluto correspondente em torno
de 1600 cm−1. Atrav´es da parametrizac¸˜ao do modelo NDDO-CIS implementado no programa
ORCA foi poss´ıvel obter um modelo semiemp´ırico para o c´alculo da energia tripleto de complexosdelantan´ıdeocom
qualidade bem superiora da melhormetodologiaTDDFT avaliada. / Theoretical methodologies are useful to complement experimental investigations, and to guide
new experiments involving luminescent lanthanide compounds. The lack of a software containing
these methods motivated us to the development of the user friendly software package
LUMPAC. And indeed, LUMPAC is slowly popularising the use of these theoretical methodologies
- methodologies that are being put to more frequent tests, and are, consequently, slowly
revealing their limitations. In this sense, we identified which aspects of the methods would
deserve a more special attention, namely: intensity parameters calculations (Ωλ), calculation
of the excited state energies of the ligands, and the calculation of the non-radiative decay rate
(Anrad). The overall objective of this doctoral work is to correct some of these limitations as
wellastoadvancenewdevelopments. RegardingtheΩλ calculation,wemitigatedthisproblem
with a new way to adjust the charge factors and polarizabilities through a procedure we called
theQDC Uniqueness Model, which makes use of a fairly small set of adjustaeble parameters
(Q,D, andC). The importance of theQDC adjustment is that all derived quantities become
also unique for a given complex geometry, including the chemical partition of the radiative
emission rate (Arad) in terms of the effects of the ligands, which is being advanced here. To
demonstrate one of the possible applications of this chemical partition, we address the case of
repeating non-ionic ligand ternary complexes of europium(III) with DBM, TTA, and BTFA.
The chemical partition perfectly ordered the non-obvious combination of pairs of non-ionic ligands
that led to the mixed ligand compounds with the highest values ofAexp
rad . Regarding the
calculation of the excited states of the ligands, a new parametrization of the CIS method based
on the NDDO approximation is being proposed, exclusively for lanthanide complexes. In
addition, we carried out a study to evaluate some TDDFT methodologies for the calculation of
excited states of ligands in lanthanide complexes. Among the functionals and basis sets evaluated,
the combination LC-ωPBE/6-31G(d) was the one that led to the lowest UME (unsigned
mean error), of around 1600 cm−1, for the triplet energies in comparison with data from the
literature. The parametrization of the NDDO-CIS model implemented into ORCA provided
a semiempirical method for the triplet energy calculation of lanthanide complexes with better
predictionpower thanthebestassessed TDDFT method.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufpe.br:123456789/20175 |
| Date | 26 January 2017 |
| Creators | DUTRA, José Diogo de Lisboa |
| Contributors | http://lattes.cnpq.br/9039283386176018, FREIRE, Ricardo Oliveira, SIMAS, Alfredo Mayall |
| Publisher | Universidade Federal de Pernambuco, Programa de Pos Graduacao em Quimica, UFPE, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Breton |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFPE, instname:Universidade Federal de Pernambuco, instacron:UFPE |
| Rights | Attribution-NonCommercial-NoDerivs 3.0 Brazil, http://creativecommons.org/licenses/by-nc-nd/3.0/br/, info:eu-repo/semantics/openAccess |
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