Bisarylselanylbenzo‐2,1,3‐selenadiazoles: Synthesis, Photophysical, Electrochemical and Singlet‐Oxygen‐Generation Properties

Abstract

We describe herein our results on the synthesis of bisarylselanylbenzo‐2,1,3‐selenadiazoles through double cross‐coupling reaction. The named compounds were obtained in moderate to good yields by reactions of a range of diaryl diselenides with the 4,7‐dibromobenzo[c][1,2,5]selenadiazole using 20 mol‐% of CuO nanoparticles as a catalyst. In addition, the obtained compounds were investigated regarding their photophysical properties in solution and singlet oxygen generation. Bisarylselanylbenzo‐2,1,3‐selenadiazoles presents strong absorption bands at UV region and red emission properties, depending on the substituent. Geometrical, photophysical and electronic properties of the compounds are characterized with density functional theory calculations. In all derivatives are observed the oxidation process of Se atom, using electrochemical analysis. Also, the quantum yields of photosensitized 1O2 production of the synthesized compounds were slightly lower than the standard, but still displays good ability to generate singlet oxygen species. The ability to generate 1O2 of benzo‐2,1,3‐selenadiazole derivatives after being exposed to light and oxygen allowed us to envisage them as a potential application in photodynamic therapy.

Recent Progress in Synthetic and Biological Application of Diorganyl Diselenides

“…For instance, in one application, the reaction of diaryl diselenides with 4,7‐dibromobenzoyl selenadiazoles employing CuO nanoparticles as a catalyst resulted in the formation of bis‐arylselenyl‐benzoselenadiazoles 115 through a double cross‐coupling process (Scheme 108). [167] The products were obtained in satisfactory yields using 20 mol % of the copper salt, demonstrating efficacy in catalyzing the cross‐coupling of diaryl diselenides bearing electron‐donating and electron‐withdrawing substituents directly attached to the aromatic ring. Additionally, copper salts have been explored for synthesizing 5‐arylselenylpyrimidine and 7‐arylselenyl‐7‐deazapurine nucleosides and nucleotides.…”

Activation by Glutathione in Hypoxic Environment of an Azo‐based Rhodamine Activatable Photosensitizer. A Computational Elucidation

“…While the proposed addition of bromine substituents to the xanthylium nucleus to enhance the 1 O 2 generation did not improve the maximum absorption, [24–26] other rhodamine derivatives have been prepared replacing oxygen in the xanthylium core with selenium. The selenium enclosure is, indeed, widely used to improve the performance of several chromophores as either fluorescence probes or photosensitizers [13,27–31] . This structural modification in rhodamine not only improves the 1 O 2 quantum yields, but also grantees the light absorption within the therapeutic window [20,22,23,32] .…”