Synthesis and characterization of a benzoic acid functionalized aza-bodipy derivative as a photosensitizer for dye-sensitized solar cells Saadet Elif Duran, Şennur Özçelik, Ahmet Gül Istanbul Technical University, Turkey Dye-sensitized solar cells (DSSCs) belong to the category of third-generation solar cells that strive to surpass the constraints associated with silicon-based photovoltaic cells. Their objective is to address the limitations inherent in traditional silicone-based solar celltechnology. 1 In the recent years, ruthenium dyes in DSSC designs are being replaced by organic dyes due to their environmental friendliness and ease of their preparation. 2 BF 2 + chelate of aza-dipyrromethenes (aza-BODIPY) is a versatile group of highly stable synthetic dyes with tunable absorption and emission properties. Considering their excellent optical and electrochemical features, such as intense absorption in the visible region, high absorptivity coefficient and high quantum yield, high photostability and chemical stability, aza-BODIPYs can be a good candidate for photosensitizers in DSSCs. The primary objective of this study was to synthesize and characterize a novel aza-BODIPY molecule functionalized with ethynylbenzoic acid groups at the pyrrolic positions, with the intention of utilizing it as a photosensitizer in DSSCs. For the preparation of the target aza-BODIPY derivative, tetraphenyl aza-dipyrromethene compound was prepared by the reported procedure with some modifications. 3 Bromination of the core positions of this aza-dipyrromethene derivative was achieved by reacting with N-Bromosuccinimide. Functionalization of this brominated aza dipyrromethene compound with 4-ethynylbenzoic acid via palladium catalyzed Sonogashira coupling reaction resulted in the formation of aza-dipyrromethene bearing benzoic acid groups. The target aza-BODIPY derivative was prepared by reaction of the aza-dipyrromethene derivative with boron trifluoride etherate in the presence of N,N-diisopropylethylamine. aza-BODIPY compound carrying ethynylbenzoic acid groups at its core positions was characterized by using UV-Vis, fluorescence, 1 H-NMR and mass spectroscopy techniques.
Figure 1. Benzoic acid functionalized aza-BODIPY derivative. References 1. Tomar, N.; Agrawal, A.; Dhaka, V. S.; Surolia, P. K., Ruthenium complexes based dye sensitized solar cells: Fundamentals and research trends. Solar Energy 2020, 207 , 59-76. 2. Iqbal, M. Z.; Ali, S. R.; Khan, S., Progress in dye sensitized solar cell by incorporating natural photosensitizers. Solar Energy 2019, 181 , 490-509. 3. Esquivel, E. C. C.; Rufino, V. C.; Nogueira, M. H. T.; Souza, A. C. C.; Júnior, J. R. P.; Valle, M. S., Synthesis and characterization of 1, 3, 5-triarylpyrazol-4-ols and 3, 5-diarylisoxazol-4-ols from chalcones and theoretical studies of the stability of pyrazol-4-ol toward acid dehydration. Journal of Molecular Structure 2020, 1204 , 127536.
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