Novel BODIPY-Cyclotriphosphazene- Fullerene triads: Synthesis, characterization and singlet oxygen generation efficiency

Novel heavy atom free triad type triplet photosensitizers composed of unsubstituted and distyryl BF2-chelated dipyrromethene (BODIPY), cyclotriphosphazene and fullerene- C-60, were newly synthesized using multistep synthetic procedure. Rigid cyclotriphosphazene core enabled fated non-geminal-cis-tris arrangement of chromophores (BODIPY) and fullerene- C60 as spin converter. All newly synthesized compounds were characterized by MALDI-MS, H-1, C-13 and P-31 NMR. Optical absorption and emission studies were systematically performed in solution by comparing with the reference compounds to establish the photophysical properties of the triads. The new heavy atom free triplet photosensitizers contain three light harvesting antennas as well as combined with different absorption wavelengths resulting in high molar extinction coefficients. Singlet oxygen generation capacities of novel triads are measured using the trap molecule 1,3-diphenylisobenzofuran. Also, both triads demonstrate chemical and photo stability under the environment of singlet oxygen measurement.