Sensitive and selective detections of mustard gas and its analogues by 4-mercaptocoumarins as fluorescent chemosensors in both solutions and gas phase

Mustard gas has been used as a chemical warfare agent for a century, and is the most likely chemical weapon used in wars or by terrorists. Thus, it is important to develop a facile, rapid and highly selective method for the detection of mustard gas. In this paper, two fluorescent probe molecules, 4-mercaptocoumarins, have been developed for rapid and sensitive detections of SM and its analogues (CEES and NH1) in both solutions and gas phase. The sensing reaction is a nucleophilic addition at three-membered hetercyclic sulfonium/ammonium formed from SM, CEES/NH1 in ethanol. Two fluorescent probes (4-mercaptocoumarins, ArSH) in ethanol deprotonate to form thiophenol anions (ArS-) resulting from their low pKa values (3.2-3.4), and the nucleophilic addition of the anion ArS generates the corresponding thioethers, giving a turn-on fluorescence response. The thiophenol anion can fast sense SM, CEES and NH1 (within 1-4 min) with high sensitivity (similar to nM level) at 60 degrees C, and high selectivity through adding a tertiary amine, and two probes exhibit excellent chemical and photostability in detection systems. Furthermore, a facile test strip with the sensor was fabricated for the detection of CEES vapor with rapid response (3 min), high sensitivity (9 ppb) and high selectivity.

Automated summary

Two fluorescent probe molecules have been developed for rapid and sensitive detections of mustard gas and its analogues in both solutions and gas phase. The method can quickly detect mustard gas at 60 degrees Celsius with high sensitivity and excellent stability in the detection systems.