Singlet oxygen quantum yield determination for a fluorene-based two-photon photosensitizer

Area of Science:

• Photochemistry
• Organic Chemistry
• Biomedical Optics

Background:

• Singlet oxygen generation is crucial for photodynamic therapy and other biomedical applications.
• Two-photon excitation offers advantages for deep tissue penetration and reduced photodamage.
• Developing efficient two-photon photosensitizers (PS) is essential for advancing these fields.

Purpose of the Study:

• To determine the quantum yield of singlet oxygen generation for a specific fluorene derivative under two-photon excitation.
• To evaluate the potential of this fluorene derivative as a two-photon PS for near-infrared applications.
• To characterize its two-photon absorption properties.

Main Methods:

• A photochemical method was employed using 1,3-diphenylisobenzofuran (DPBF) as a singlet oxygen quencher.
• The fluorene derivative 2-(9,9-didecyl-7-nitrofluoren-2-yl)benzothiazole (1) was used as the two-photon photosensitizer.
• Photochemical kinetics were measured using fluorescence spectroscopy.

Main Results:

• The fluorene derivative (1) exhibited a high singlet oxygen quantum yield (Phi(Delta) ≈ 0.4 ± 0.1).
• A two-photon absorption cross-section of 28 ± 5 GM was determined for the photosensitizer.
• The compound demonstrated efficient singlet oxygen generation under two-photon excitation.

Conclusions:

• The fluorene derivative (1) is a promising candidate for a two-photon photosensitizer.
• Its properties are suitable for applications in the near-infrared spectral region.
• Further investigation for biomedical applications is warranted.