An efficient ESIPT-based ratio-/fluorimetric probe for rapid and sensitive detection of the sarin surrogate diethylchlorophosphate in solution and vapor phases†

Abstract

Nerve agents are highly toxic compounds that are based on organophosphorus chemistry, and their use is banned by international treaties regarding chemical weapons. Among the various nerve agents, sarin is highly lethal and inhibits the neuronal transmission and signaling of acetylcholinesterase. This study reports a fluorescent probe, (E)-3-(((2-(1H-benzo[d]imidazole-2-yl)phenyl)imino)methyl)-2-methoxy-2H-chromen-4-ol (BPMC), that demonstrates exceptional efficiency in detecting diethylchlorophosphate (DCP), a sarin surrogate, in solution and vapor phases. The gradual addition of DCP to the probe solution leads to a turn-on photoluminescence transition from blue to cyan because of the extension of intramolecular charge transfer transition (ICT) and inhibition of the excited-state intramolecular proton transfer (ESIPT) process. The minimum levels of DCP for detection and quantification were determined to be 6.6 μM and 22 μM, respectively, in the presence of various analogous analytes. Additionally, a test kit made of strips of cellulose paper was successfully assembled for real-time application. Dip-stick and dip-vial-conical-flask analyses were demonstrated as effective tools for detecting and quantifying DCP in the vapor phase. Furthermore, a smartphone-based approach was executed for the practical application of BPMC, enabling immediate identification and quantification of DCP in actual danger scenarios. Thus, this work presents a new ratiometric fluorogenic probe for the detection of sarin surrogate with potential application in actual hazardous situations.