Banca de QUALIFICAÇÃO: ALEXANDER GARRETA GONCALVES COSTA PINTO
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.DISCENTE : ALEXANDER GARRETA GONCALVES COSTA PINTO
DATA : 19/12/2019
HORA: 09:00
LOCAL: sala 304, 3º andar, Bloco B, Campus SA da Fundação Universidade Federal do ABC, localizada na Avenida dos Estados, 5001, Santa Terezinha, Santo André, SP
TÍTULO:
Use of 1,2,4,5-tetraphenylimidazole derivatives in organic light emitting systems
PÁGINAS: 25
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Físico-Química Orgânica
RESUMO:
Fourteen 1,2,4,5-tetraphenylimidazole derivatives containing electron-donating and withdrawing substituents at the N-phenyl ring were synthetized, and divided in two paired series of seven compounds differing in the presence of a hydroxyl group (–OH) on the 2-phenyl ring. Their photophysical, chemiluminescent and electrochemical characteristics were determined in order to use these compounds as activators (ACT) in the chemiluminescent peroxyoxalate reaction. The series without hydroxyl has shown similar values of fluorescence quantum yield (ΦFL, between 0.21 and 0.33). The presence of –OH caused, in general, reduced ΦFL values relative to the other series, due to an intramolecular proton transfer process (ESIPT) that affects the properties of these molecules. For this series with –OH, a Hammett plot with ρ = –0,8 indicated that the fluorescence process is sensible to the substituent electronic character. The bromine-substituted compounds have shown the lowest ΦFL values, ca. 0.03, due to the heavy atom effect. The strong deactivating nature of the –NO2 group resulted in higher ΦFL values in these correlates. Kinect light emission assays were performed and showed that the tested compounds acted as ACTs in the peroxyoxalate reaction, since the observed rate constants of the process (kobs1 e kobs2) did not change with their concentration. Through cyclic voltammetry, values for the oxidation potential (Eox) were determined and they are in a wide range from 1,00 to 1,42 V vs. SCE. These values are related to an electron transfer mechanism in chemiexcitation and may be associated to the character of the substituent.
MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1939561 - FERNANDO HEERING BARTOLONI
Membro Titular - Examinador(a) Interno ao Programa - 1654772 - CAMILO ANDREA ANGELUCCI
Membro Titular - Examinador(a) Interno ao Programa - 1623577 - JOAO HENRIQUE GHILARDI LAGO
Membro Suplente - Examinador(a) Externo ao Programa - 1909951 - ARTUR FRANZ KEPPLER