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

Author(s):Show less -

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

• Document type: Journal article
• Source: Physical Chemistry Chemical Physics; v. 25, n. 6, p. 8-pg., 2023-01-13.

Abstract

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)

• FAPESP's process: 18/11283-7 - Nonlinear photonics: spectroscopy and advanced processing of materials
• Grantee: Cleber Renato Mendonça
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/20886-1 - Ultrafast nonlinear optical spectroscopy: Transient Absorption and optical Kerr Gate with polarization control
• Grantee: Leonardo de Boni
• Support Opportunities: Regular Research Grants
• FAPESP's process: 20/16036-8 - Ultrafast spectroscopy: degenerated and non-degenerated pump-probe resolved in polarization
• Grantee: Rafael de Queiroz Garcia
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 22/06561-3 - 6th International Workshop on Nano and Biophotonics
• Grantee: Leonardo de Boni
• Support Opportunities: Research Grants - Meeting - Abroad