Dibenzononazethrene Isomers: Stable Singlet Diradicaloids with Efficient Photothermal Conversion

Area of Science:

• Organic Chemistry
• Materials Science
• Photomedicine

Background:

• Organic singlet diradicaloids are effective photothermal agents due to strong light absorption and heat conversion.
• Developing stable diradicaloids for biomedical applications is crucial.

Purpose of the Study:

• To synthesize and characterize stable dibenzononazethrene isomers (DBNZ1 and DBNZ2).
• To evaluate their photothermal conversion efficiency and potential for cancer therapy.

Main Methods:

• Synthesis of DBNZ1 and DBNZ2 via a concise method.
• Characterization using theoretical and experimental techniques to confirm diradical nature.
• Spectroscopic analysis for light absorption and photothermal conversion.
• Nanoparticle formulation (DBNZ1-NPs) and in vitro photothermal therapy studies.

Main Results:

• DBNZ1 and DBNZ2 exhibit open-shell singlet diradical ground states (diradical indices 0.67 and 0.69).
• Efficient light absorption in the far-red region and high photothermal conversion efficiency (72.9% for DBNZ1-NPs).
• DBNZ1-NPs showed biocompatibility and efficacy in tumor ablation in vitro when activated by an 808 nm laser.

Conclusions:

• DBNZ1 and DBNZ2 are stable organic singlet diradicaloids with excellent photothermal properties.
• DBNZ1-based nanoparticles are promising, biocompatible agents for laser-activated cancer photothermal therapy.