Benzthiazole-derived chromogenic, fluorogenic and ratiometric probes for detection of hydrazine in environmental samples and living cells

Abstract

Abstract Benzothiazole-based chromogenic and ratiometric fluorescent chemodosimetric probes CD1 and CD2, were synthesized and characterized. The probes are designed in such a way that the excited state intramolecular proton transfer (ESIPT) of the benzothiazole moiety gets blocked. Upon treatment with hydrazine in organo-aqueous medium[DMSO: H2O; 2:1 (v/v)] at physiological pH, the aectyl protective group of probes CD1 and CD2 were removed readily in presence hydrazine and ESIPT of the probes were switched on, which resulted remarkable photo-physical changes. These two ESIPT–based ratiometric fluorescent probes were shown to be selective and sensitive for hydrazine among different cations, anions and amines studied in organo-aqueous medium[DMSO: H2O; 2:1 (v/v)] at physiological pH, by fluorescence, absorption, and visual emission color change. These key features allows the two probes to be employed for hydrazine detection by simple visual inspection. DFT and TDDFT calculations were performed in order to demonstrate the sensing mechanism and the electronic properties of probe and hydrazinolysis product. An easy-to-prepare test strips, obtained by dipping the TLC plates into the solution of CD1 and CD2, were able to detect hydrazine in practical samples. Moreover, the utility of the probes CD1 in showing the hydrazine recognition in live cells has also been demonstrated using Vero cells as monitored by fluorescence imaging.