Benzothiazole‐based chemosensor: a quick dip into its anion sensing mechanism

Abstract

AbstractDensity functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) methods have been applied to decipher the F− anion sensing mechanism of a fluorescent probe N‐(2‐(benzothiazole‐2‐yl)phenyl)‐4‐methoxybenzamide (4). The amidic proton (N–H) of the selected probe may exhibit an intramolecular hydrogen bond (IMHB) with the nitrogen atom of benzothiazole moiety. The weak IMHB of N24–H26‐‐‐N12 in the excited state favors reverse proton transfer process in 4. In the ground state of 4, the F− anion interacts via F−‐‐‐H–N bond, which immediately deprotonates the amidic proton, leading to the distortion of the geometry. Subsequent to deprotonation, the significant intramolecular charge transfer (ICT) character was observed in 4. On account of the significant ICT process, the redshift in absorption and emission spectra was observed. These outcomes were employed to delineate the sensing mechanism of molecule 4.