Contrasting photophysical properties of rhenium(I) tricarbonyl complexes having carbazole groups attached to the polypyridine ligand

Autor(es)

Ramos, L. D. ; Sampaio, R. N. ; de Assis, F. F. ; de Oliveira, K. T. ; Homem-de-Mello, P. ; Patrocinio, A. O. T. ; Frin, K. P. M.

• Tipo de documento: Artigo Científico
• Fonte: DALTON TRANSACTIONS; v. 45, n. 29, p. 11688-11698, 2016.
• Citações Web of Science: 13

Resumo

In the present work, new rhenium(I) polypyridyl compounds, fac-{[}Re(L)(CO)(3)(cbz(2)phen)](+/0) where cbz(2)phen = 4,7-di(9H-carbazol-9-yl)-1,10-phenanthroline and L = Cl-, pyridine (py) or 2-aminomethylpyridine (ampy) were synthesized and characterized by H-1 NMR, UV-Vis and IR spectroscopy combined with theoretical calculations using time-dependent density functional theory (TD-DFT). Their photophysical properties were investigated by steady state and time-resolved emission spectroscopy. These compounds show a strong and broad absorption band around 350-500 nm that, also by TD-DFT, corresponds to the carbazol -> phenanthroline intraligand charge transfer transition, (ILCTcbz2phen)-I-1, with some contribution of the Re(I) -> phenanthroline metal-to-ligand charge transfer transition, (MLCTRe -> cbz2phen)-M-1. In contrast to typical Re(I) polypyridyl complexes, cbz(2)phen-based Re(I) compounds exhibit two emission maxima in CH3CN solution and relatively low emission quantum yields, 10(-3)-10(-2). Solution phase time-resolved photoluminescence and excited state quenching experiments provided meaningful information on the presence of multiple emitter states after light excitation, which were identified as an (ILCTcbz2phen)-I-1 excited state deactivation at higher energies and a long-lived phosphorescence attributed to the (MLCTRe -> cbz2phen)-M-3 excited state. When embedded into a PMMA matrix, the radiative decay from the singlet state is inhibited and the contribution of both (MLCT)-M-3 and 3(I)LCT(cbz2phen) to the luminescence is observed. The photophysics of these Re(I) compounds reported herein provide new insights into the understanding of substitutional groups on the polypyridyl ligands that are relevant to practical and fundamental development of photo-induced molecular devices. (AU)

• Processo FAPESP: 15/21110-4 - Explorando Reações Fotocatalisadas em Condições de Fluxo Contínuo pelo uso de Sistemas Porfirinóides: (C-FlowPhotoChem)
• Beneficiário: Kleber Thiago de Oliveira
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 11/23408-0 - Síntese, caracterização e investigação das propriedades fotofísicas de complexos de rênio (I)
• Beneficiário: Karina Passalacqua Morelli Frin
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 12/24096-4 - Reações de Acoplamento Cruzado em Tetrabromobacterioclorinas: Abordagens para a Síntese de Sistemas de Alta Conjugação
• Beneficiário: Francisco Fávaro de Assis
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 13/06532-4 - Reações de acoplamento cruzado na síntese de novos fotossensibilizadores de alta conjugação
• Beneficiário: Kleber Thiago de Oliveira
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 15/13149-8 - Complexos polipiridínicos de rênio(I): síntese, investigação das propriedades fotofísicas e aplicação como sondas luminescentes e/ou agentes terapêuticos
• Beneficiário: Karina Passalacqua Morelli Frin
• Modalidade de apoio: Auxílio à Pesquisa - Regular