An indolizine-derived chemodosimeter with enhanced emission in a micellar environment for ppb-level detection of mercury ions

Abstract

Mercury is a harmful heavy metal that gravely threatens the environment and organisms. In the current study, 2-(1,3-oxathiolan-2-yl)-1,3-diphenylindolizine (DPIC-OS) and 2-(1,3-dithiolan-2-yl)-1,3-diphenylindolizine (DPIC-SS) probes are designed by protecting a 1,3-diphenylindolizine-2-carbaldehyde (DPIC-CHO) with mercury-recognizable 1,3-dithiolane and 1,3-oxathiolane moieties and utilized for the selective detection of Hg²⁺ ions in a micellar medium. Hydrophobic probes DPIC-OS and DPIC-SS exhibit intense fluorescence in the confined environment of a micellar solution. A significant enhancement in fluorescence intensity was seen for these probes upon switching from organic to aqueous micellar media. Upon the incremental addition of Hg²⁺ ions, the probes display a fluorescence shift, exhibiting a bluish-green emission at 505 nm through the release of fluorescent DPIC-CHO in the working solution by the spontaneous cleavage of the thioacetal linkage. DPIC-OS was more efficient than DPIC-SS, and subsequent analytical studies were conducted with this probe. The DPIC-OS exhibited no or insignificant response towards numerous common anions, cations, and small molecules, affirming its selectivity to Hg²⁺ ions and offering a low limit of detection (LOD) of 3.2 ppb (16.2 nM). The real-sample analysis by spiking mercury ions in water showed excellent percentage recoveries.