Unveiling the molecular structure and two-photon absorption properties relationship of branched oligofluorenes

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Cocca, Leandro Zucolotto H. ; Pelosi, Andre Gasparotto ; Abegao, Luis M. G. ; Garcia, Rafael de Q. ; Mulatier, Jean-Christophe ; Pitrat, Delphine ; Barsu, Cyrille ; Andraud, Chantal ; Mendonca, Cleber R. ; Vivas, Marcelo G. ; De Boni, Leonardo

• Tipo de documento: Artigo Científico
• Fonte: Physical Chemistry Chemical Physics; v. 25, n. 6, p. 8-pg., 2023-01-13.

Resumo

Organic molecules have been intensively studied during the last few decades because of their photonics and biological applications. In this material class, the fluorene molecules present outstanding optical features, for example, high values of two-photon absorption (2PA) cross-sections, visible transparency, and high fluorescence quantum yield. Also, it is possible to improve the nonlinear optical response by modifying the fluorene molecular structure. In this context, herein, we have synthesized V and Y-shaped branching oligofluorenes containing two and three fluorene moieties in each branch. Such a molecular strategy may exponentially enhance the nonlinear optical response due to the coherent coupling among the molecular arms. Thus, we combined the use of femtosecond Z-scan spectroscopy and white light transient absorption spectroscopy (TAS) to understand the molecular structure and 2PA property relationship of branching oligofluorenes. The results show that there is a universal relationship between the 2PA cross-section and the effective pi-electron number (N-eff) given by sigma(2PA)(GM) = (079 +/- 0.03)N-eff(2), which is independent of the molecular shape (linear, V or Y-shaped). Therefore, the intramolecular charge transfer responsible for the cooperative effect among the branches does not occur. This statement is corroborated by the results of the femtosecond TAS technique. (AU)

• Processo FAPESP: 18/11283-7 - Fotônica não linear: espectroscopia e processamento avançado de materiais
• Beneficiário: Cleber Renato Mendonça
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• 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
• Processo FAPESP: 20/16036-8 - Espectroscopia ultrarrápida: excitação e prova degenerados e não degenerados resolvidos em polarização
• Beneficiário: Rafael de Queiroz Garcia
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 22/06561-3 - 6th International Workshop on Nano and Biophotonics
• Beneficiário: Leonardo de Boni
• Modalidade de apoio: Auxílio à Pesquisa - Reunião - Exterior