Banca de DEFESA: DOUGLAS SALGADO DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : DOUGLAS SALGADO DA SILVA
DATE: 26/04/2024
TIME: 14:00
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

COMPUTATIONAL MODELING OF LUMINESCENT HYBRIDS WITH Eu3+

KEY WORDS:

Computational chemistry, Lanthanides, Europium, Luminescent Materials.

PAGES: 64
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

Among nanometric materials, mesoporous silica (SiO2) has been gaining prominence due to the possibilities of applications in different areas according to the size of the nanoparticle. The synthesis of hybrid materials, obtained by supporting trivalent europium ion (Eu3+) complexes on silica nanospheres of the MCM48 type using ligands derived from trimesic acid (BTC) and chelidamic acid (DAMIC), motivated this work, due to the potential for use of these materials to make paints and act in security devices. Thus, a molecular model was proposed to understand the intramolecular energy transfer mechanism that leads to the luminescence of hybrid materials of this type. The modeled structures were obtained with the calculation level PBE1PBE/MWB52/6-31G(d) and AM1/Sparkle. The energy levels of the singlet and triplet excited states, obtained from TD-DFT calculations at the LC-wPBE/MWB52/6- 31G(d) level, showed that the complexes studied tend to present luminescence, in agreement with the experimental data. The calculation of Judd-Ofelt intensity parameters was performed using the chemical bond overlap polarizability model implemented on the JOYSpectra web platform. The calculation of intramolecular energy transfer rates was carried out using the method proposed by Malta and collaborators (2019); and the calculation of luminescence lifetime and luminescence quantum yield, based on solving the rate equations numerically using the fourth order Runge-Kutta method with adaptive time step. The structural model proposed for complexes with btfa ligands provides data compatible with experimental data. The results provide more favorable energy transfer mechanisms via the triplet state of the ligand to the 5DJ level (J = 0, DAMIC and J = 1, BTC) of the ion, followed by transfer via the singlet state to the 5G2 level. Future measurements of quantum yield (Q%) may help to understand the differences in the luminescence process related to the intrinsic characteristics of the ligands, evaluated by proposing three scenarios (Q% = 1, 20 and 50). The proposed model and procedures used in this work were appropriate and could assist in the investigation of new systems that enable the development of more efficient devices.

COMMITTEE MEMBERS:
Externa à Instituição - KEYLA MIRELLY NUNES DE SOUZA - IFBA
Externo à Instituição - LEONIS LOURENÇO DA LUZ
Presidente - 1354207 - SEVERINO ALVES JUNIOR