Near‐Infrared BODIPY‐Acridine Dyads Acting as Heavy‐Atom‐Free Dual‐Functioning Photosensitizers

Boron dipyrromethene (BODIPY) dyes represent a particular class within the broad array of potential photosensitizers. Their highly fluorescent nature opens the door for theragnostic applications, combining imaging and therapy using a single, easily synthesized chromophore. However, near‐infrared abs...

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Bibliographic Details
Published in:Chemistry : a European journal 2020-11, Vol.26 (66), p.15212-15225
Main Authors: Deckers, Jasper, Cardeynaels, Tom, Penxten, Huguette, Ethirajan, Anitha, Ameloot, Marcel, Kruk, Mikalai, Champagne, Benoît, Maes, Wouter
Format: Article
Language:English
Subjects:
Acridine
BODIPY dyes
Boron
Charge transfer
Chemistry
Chromophores
Cytotoxicity
Fluorescence
Infrared absorption
near-infrared
Oxygen
Photodynamic therapy
photosensitizers
Singlet oxygen
Toxicity
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Summary:Boron dipyrromethene (BODIPY) dyes represent a particular class within the broad array of potential photosensitizers. Their highly fluorescent nature opens the door for theragnostic applications, combining imaging and therapy using a single, easily synthesized chromophore. However, near‐infrared absorption is strongly desired for photodynamic therapy to enhance tissue penetration. Furthermore, singlet oxygen should preferentially be generated without the incorporation of heavy atoms, as these often require additional synthetic efforts and/or afford dark cytotoxicity. Solutions for both problems are known, but have never been successfully combined in one simple BODIPY material. Here, we present a series of compact BODIPY‐acridine dyads, active in the phototherapeutic window and showing balanced brightness and phototoxic power. Although the donor–acceptor design was envisioned to introduce a charge transfer state to assist in intersystem crossing, quantum‐chemical calculations refute this. Further photophysical investigations suggest the presence of exciplex states and their involvement in singlet oxygen formation. A series of compact, heavy‐atom‐free, BODIPY‐acridine photosensitizers are presented that are activated by near‐infrared light and show balanced brightness and phototoxic power. The BODIPY chromophores are subjected to extensive photophysical characterization and quantum‐chemical calculations, suggesting the involvement of exciplex states in singlet oxygen formation.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.202002549