A benzothiazole-based new fluorogenic chemosensor for the detection of CN and its real-time application in environmental water samples and living cells.

Since the cyanide ion is used in a wide range of industries and is harmful to both human health and the environment, a number of research efforts are dedicated to creating fluorescence sensors for the detection of cyanide (CN). Herein, for the fluorescence detection of CN, a new highly selective and sensitive sensor 2-(3-(benzo[]thiazol-2-yl)-4-hydroxybenzylidene)-1-indene-1,3(2)-dione (BID) was created by conjugating a benzothiazole moiety with 1-indene-1,3(2)-dione. The donor and acceptor components of this hybrid receptor were covalently connected through a double bond. The nucleophilic addition of a cyanide anion to the BID inhibits the intramolecular charge transfer (ICT) transition, resulting in spectral and colour alterations in the receptor. When the solvent polarity was increased from -hexane to methanol, this molecule exhibited a bathochromic shift in the emission wavelength (610 to 632 nm), suggesting the presence of a solvatochromic action. The sensor BID has shown strong specificity towards CN by interrupting its internal charge transfer (ICT), resulting in a significant change in the UV-vis spectrum and a notable blue shift in the fluorescence emission spectrum. The cyanide anion (CN) is responsible for the optical alterations observed by BID, as opposed to the other anions examined. The detection limit was 5.97 nM, significantly less than the WHO's permitted amount of CN in drinking water. The experimental findings indicate that BID's fluorescence response to CN is pH insensitive throughout a wide pH range of 6.0 to 12.0. The interaction mechanism between the BID and CN ions has been studied by HRMS, H-NMR titration experiments, FT-IR, and DFT, which confirmed the nucleophilic addition of CN on vinylidene and subsequent disturbance of ICT. Additionally, we demonstrated the real-time detection application of CN in environmental water samples and live-cell imaging.