Green synthesis of a benzothiazole based ‘turn-on’ type fluorimetric probe and its use for the selective detection of thiophenols in environmental samples and living cells

Abstract

We have developed an efficient turn-on type fluorescent chemodosimeter for the detection of aromatic thiols in aqueous media. The probe was successfully synthesized by condensation of 2-aminothiophenol with salicylaldehyde followed by S_NAr with 2,4-dinitrochlorobenzene in one-pot in a micellar medium. The function of the probe is attributed to the thiol driven cleavage of the dinitrophenyl ether linkage of probe 1 to release 2-(2-hydroxyphenyl)benzothiazole (2) which shows strong greenish fluorescence by excited-state intramolecular proton transfer (ESIPT). The probe is highly selective for aromatic thiols in the presence of several aliphatic thiols, including biologically important thiol-containing amino acids. The utility of the probe was successfully demonstrated in the detection of thiophenols in real samples and in living cells. A hazardless synthetic procedure, cost effective single-step synthesis, high selectivity and sensitivity, fast signal transduction and low limit of detection (3.3 ppb) are some of the key merits of this analytical tool.