Discrimination of tabun mimic diethyl cyanophosphonate from sarin mimic diethyl chlorophosphate via Zn(II)-triggered photoinduced electron transfer-decoupled excited state intramolecular proton transfer processes

Herein, for the fluorogenic and naked eye detection and discrimination of the environmentally and biologically important tabun mimic diethyl cyano phosphonate (DCNP) and sarin mimic diethyl chloro phosphate (DCP) in one platform, a smart probe was designed and synthesized. 2-(2'-Hydroxyphenyl)benzothiazole (HBT) was fused with fluorescein hydrazide (PET-coupled 2-way-ESIPT system) for this purpose, but the response obtained was just off-on type. Among the metal ions, the receptor can easily detect Zn2+ from other common metal ions. When we used the FHC-Zn2+ complex for the discrimination of DCNP from DCP, the result was very satisfactory. FHC-Zn2+ complex can detect DCP in a ratiometric manner and DCNP in an off-on manner. In this method, under UV light, it is possible to distinguish the color change with the naked eye. The sensing mechanism has been explained via Zn2+-triggered PET-decoupled ESIPT processes. Vapour phase sensing was also performed to show the potential for the real applications of the probe.