Novel BODIPY-bridged cyclotriphosphazenes


Abstract: Three new 2-component unsubstituted (4P), diiodo- (5P), and dibromo- (6P) distyryl-BODIPY-bridged cyclotriphosphazene dimers were designed and synthesized. The newly synthesized BODIPY-cyclotriphosphazene systems were characterized by $^{1}$H, $^{13}$C, and $^{31}$P NMR spectroscopy. The photophysical properties of the distryl-BODIPYs (4-6) and BODIPY-cyclotriphosphazene dyads (4P-6P) were studied by UV-Vis absorption and fluorescence emission spectroscopy. In these derivatives, the bino-type cyclotriphosphazene derivative bearing unsubstituted BODIPY unit 4 P exhibited high fluorescence and no singlet oxygen generation due to the lack of spin converter. The attachment of heavy atoms (iodine and bromine) enabled the production of singlet oxygen. The bino-type BODIPY-cyclotriphosphazenes (5P and 6P) were also used as triplet photosensitizers in the photooxidation of 1,3-diphenylisobenzofuran to endoperoxide via generation of the singlet oxygen in dichloromethane. The singlet oxygen production of these compounds was also investigated via a direct method and produced a singlet oxygen phosphorescence peak at 1270 nm.

Keywords: Boron-dipyrromethene, cyclotriphosphazene, photophysical, UV-Vis spectroscopy, photochemical

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