Investigation of excited singlet state absorption and intersystem crossing mechanism of isomeric meso-tetra(pyridyl) porphyrins containing peripheral polypyridyl platinum(II) complexes

Autor(es)

Cocca, Leandro H. Z. ^[1] ; Gotardo, Fernando ^[1] ; Sciuti, Lucas F. ^{[2, 1]} ; Acunha, Thiago V. ^[3] ; Iglesias, Bernardo A. ^[3] ; de Boni, Leonardo ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, CP 369, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Escola Engn Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[3] Univ Fed Santa Maria, Dept Quim, Lab Bioinorgan & Mat Porfirin, BR-97105900 Santa Maria, RS - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Chemical Physics Letters; v. 708, p. 1-10, SEP 16 2018.
• Citações Web of Science: 6

Resumo

In the present work, the excited states (singlet and triplet) for three different porphyrins, with and without coordinated Pt(II) complex derivatives, were investigated by three different temporal laser regimes were employed in the Z-Scan technique. Intersystem crossing time (singlet to triplet conversion mechanism) was obtained by a combination of Z-Scan with single or with a train of picosecond laser pulses. These measurements have shown that the excited state absorption spectrum shows distinct absorption behaviors. Also, the absorption cross-section is equivalent to the ground state, describing no changes in the optical transmittance. Fluorescence lifetimes and quantum yields were determined, respectively, by time resolved fluorescence analysis. To determine the intersystem crossing time constant, two additional levels were incorporated to the rate equation model. Moreover, fluorescence decays, internal conversion and ISC times have shown a strong dependence in Pt(II) derivatives and their position to the porphyrin ring (meta or para position). (C) 2018 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 16/20886-1 - Modernização da linha de Espectroscopia Óptica Não Linear ultrarrápida: Absorção transiente e chave kerr óptica com controle da polarização.
• Beneficiário: Leonardo de Boni
• Modalidade de apoio: Auxílio à Pesquisa - Regular