We disclose an interesting concept for developing heavy atom-free chemiluminogenic photosensitizers. To accomplish this, conjugates 2 and 3, which are composed of boron-dipyrromethene (BODIPY) and 2,3-dihydrophthalazine-1,4-dione units, are investigated. 2 and 3 are compared in terms of their photophysical properties, chemiluminescence responses, and singlet oxygen production. Strikingly, the results indicate that decoration of BODIPY with the 2,3-dihydrophthalazine-1,4-dione scaffold boosts the singlet oxygen generation. Furthermore, treatment of epidermoid laryngeal carcinoma Hep-2 (Hep-2) cells with conjugates 2 and 3 results in efficient cellular internalization which ensures live- cell imaging of Hep-2 cells. Finally, it is noteworthy that in vitro cytotoxicity assays reveal that both 2 and 3 induce cytotoxicity when illuminated with red light. Thus, 2 and 3 represent heavy atom-free chemiluminogenic photosensitizers.
Keywords: BODIPY; CRET; chemiluminescence; heavy-atom free photosensitizer; photodynamic therapy (PDT).