Fabrication of a new fluorogenic probe for detection of phosgene in solution and vapor phase

A new fluorogenic probe, COUBM (where, COUBM = 3-(1H-benzoimidazol-2-yl)-8-benzothiazol-2-yl-chromen-2-ylideneamine) is designed and synthesized for selective and rapid detection of phosgene both in solution and gas phase. COUBM reacts with phosgene to form a cyclic carbamylated product (COUBM-PHOS) and consequently a sharp increase in fluorescence intensity is observed. The probe is efficiently used to detect phosgene in vapor phase using the COUBM loaded filter paper kit. Theoretical calculation by DFT/B3LYP/6−31+G(d) method is performed to interpret the electronic structure and the probable sensing mechanism of the probe for the detection of phosgene.