Synthesis and Photophysical Study of Bromo BODIPY as a Fluorophore for Phototheranostic Applications Rahmayani Siregar, Dikhi Firmansyah, Anas Santria, Ghalda Hanifah Pratiwi
Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology
Jalan Ganesha 10, Bandung 40132, Indonesia
Abstract
BODIPY is a fluorophore characterized by a high absorption coefficient and structural flexibility, which facilitates the tuning of its optical properties within the red-to-near-infrared spectrum. BODIPY is a promising candidate for light-based therapies, including photodynamic therapy (PDT) and photothermal therapy (PTT). Bromination of the BODIPY core has been reported to induce a bathochromic shift and increase triplet-state generation, which is ideal for biomedical applications. Additionally, fluoro substituents are known to possess high electronegativity, which can enhance the polarity of the molecule and increase its solubility. This study aimed to synthesize meso-(p-fluorophenyl) BODIPY with bromination at the beta-pyrrole position employing N-bromosuccinimide (NBS). NBS Bromination can selectively obtain the mono- and dibromo substituents by changing the equivalents. Two bromo-BODIPY derivatives were successfully obtained, as confirmed by the changes in the characteristic pyrrole signals in the H NMR spectra. The parent compound exhibited three pyrrole signals, whereas the monobrominated BODIPY compound showed four pyrrole signals, and the dibrominated BODIPY compound showed two pyrrole signals. Spectroscopic studies revealed bathochromic shifts in the absorption spectra of 23.4 nm for monobrominated and 39.2 nm for dibrominated BODIPY (the parent compound showed lambda max of 497 nm), while the fluorescence emission maxima shifted by 27.7 nm and 50 nm (the parent compound showed lambda max of 515 nm). These findings demonstrate that bromination is an effective strategy for modulating the photophysical properties of BODIPY and highlighting its potential for further development as a candidate for light-based cancer therapy.
