Photophysical behavior of meso-N-butylcarbazole-substituted BODIPY in different nano-scale organized media.

The present work focuses on the photophysical behavior of meso-N-butylcarbazole-substituted BODIPY (CBZ-BDP) in different organized media towards exploring the possible use of the dye as a molecular sensor and imaging agent. The molecule shows an appreciable change in absorption and emission spectra at 75% water-acetonitrile mixture compared to pure acetonitrile. In water-acetonitrile mixture, it displays aggregate-induced emission (AIE) bands. New emission peaks are observed at 560 nm and 630 nm, corresponding to LE (locally excited) and ICT (intramolecular charge transfer) states of CBZ-BDP aggregates. The fluorescence anisotropy studies of CBZ-BDP in glycerol medium show its better sensitivity towards the microenvironment. CBZ-BDP was used to probe various microheterogeneous systems like bile salts, pluronics, and lipid bilayer systems in aqueous medium. The dye displays sensitive variation in emission intensity and fluorescence anisotropy in sodium cholate (NaC) bile salt in aqueous medium as a function of the bile salt concentration. The molecule detects the temperature-induced phase transitions in pluronic P123 and F127, as well as 1,2-dimyristoylphosphatidylcholine (DMPC) and 1,2-dipalmitoylphosphatidylcholine (DPPC) lipid bilayer systems in aqueous medium. These studies strongly suggest that CBZ-BDP can be used as an efficient fluorescent probe in sensing the micro-environmental changes in bile salts, pluronics, and lipid bilayers in aqueous medium. The imaging studies of CBZ-BDP-embedded Giant Unilamellar Vesicles (GUVs) were carried out. The molecule stains the lipid bilayers and displays bright-green fluorescent images, suggesting its potential in lipid bilayer imaging.