A rhodamine–TPE scaffold-based fluorescent probe for visualizing phosgene with a portable smartphone via test TLC strips

Abstract

As a highly toxic commercial product, phosgene is a potentially serious threat to public safety, so a convenient and reliable phosgene detection method is urgently needed. In this work, a new through-bond energy transfer (TBET) based fluorescent probe TPE–RhodEA has been developed as a fast, susceptible, and selective sensor of phosgene. TPE–RhodEA is based on a tetraphenylethylene–rhodamine scaffold and uses ethylenediamine as the phosgene recognition unit. The probe showed blue fluorescence in acetonitrile due to the occlusion of rhodamine diamine. After reacting with phosgene, rhodamine diamine undergoes ring-opening, and TPE–RhodEA exhibits apparent red fluorescence. Due to the specific ring-opening reaction, TPE–RhodEA shows a distinct ratiometric fluorescence response to phosgene with a significant pseudo Stokes shift (267 nm), an immediate response (less than 2 min), and a low detection limit (0.54 ppm). Furthermore, TPE–RhodEA-loaded test TLC strips were prepared and enabled the direct visualization and reliable quantitative analysis of phosgene by combining fluorescent test TLC strips with an easily accessible color recognition app on a smartphone.