Banca de DEFESA: LEONARDO HENRIQUE DE MACEDO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : LEONARDO HENRIQUE DE MACEDO
DATA : 02/05/2022
HORA: 14:00
LOCAL: https://conferenciaweb.rnp.br/webconf/karina-9
TÍTULO:

Iridium(III) cyclometalated complexes: investigation of the photophysical and electrochemical properties as a function of ligands changes   

PÁGINAS: 71
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Inorgânica
ESPECIALIDADE: Foto-Química Inorgânica
RESUMO:

Iridium(III) complexes have application versatility (electroluminescent devices, catalysis, biological and chemical sensors) as they exhibit high phosphorescent quantum yields and their emission can be modulated over the entire visible spectral range. The proper choice and combination of ligands and substituents allows to regulate the excited state responsible for the emission. The present work reported the synthesis, characterization and photophysical and electrochemical properties of four bis-cyclometallated iridium(III) complexes of general structure mer-[Ir(CN)2(NN)]+ : Ir1-[Ir(ppy)2(NO2phen)]+ ; Ir2-[Ir(ppy)2(NH2phen)]+ ; Ir3-[Ir(Fppy)2(NO2phen)]+ and Ir4-[Ir(Fppy)2(NH2phen)]+ where the cyclometallated ligand CN = 2-phenyl-pyridine (ppy) or 2-(2,4-difluoro)-phenylpyridine (Fppy), and the auxiliary ligand NN, 5-amino-1,10-phenanthroline (NH2phen) or 5-nitro-1,10-phenanthroline (NO2phen). In the characterization step, spectroscopic techniques (UV/VIS absorption and emission, kinetic decay of the lifetime) and electrochemical (cyclic voltammetry and differential pulse) techniques were used. The complexes presented Ir3+/Ir4+ oxidation potential in the range of 1.27 to 1.84 V versus NHE and reduction 𝑁𝑁 /𝑁𝑁.− and 𝐶𝑁 /𝐶𝑁.−-1.04 to -0.19 V versus NHE. The presence of a multielectronic signal in the oxidation on Ir2 and Ir4 indicated that the NH2 group also participated in the oxidation. The addition of fluorine atoms to CN stabilized the HOMO energy. The NH2 group generated complexes with low 𝜙𝑒𝑚 and the NO2 group had no detectable emission, both in solution. The studies in rigid medium (PMMA) allowed to identify the profile of the emission curves of these complexes. The work showed that changes (NH2 and NO2) in the phenanthroline NN ligand drastically disturbed the energy levels of the complexes and, consequently, the nature of the excited state of the triplet (3MLCT) responsible for the emission, generating complexes with luminescent properties inferior to analogous complexes containing the 1,10-phenanthroline.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1623774 - KARINA PASSALACQUA MORELLI FRIN
Membro Titular - Examinador(a) Interno ao Programa - 1864481 - HUEDER PAULO MOISES DE OLIVEIRA
Membro Titular - Examinador(a) Externo ao Programa - 1671688 - ANDRE SARTO POLO
Membro Suplente - Examinador(a) Interno ao Programa - 1939561 - FERNANDO HEERING BARTOLONI
Membro Suplente - Examinador(a) Externo à Instituição - ANTONIO OTÁVIO DE TOLEDO PATROCÍNIO - UFU