A novel fluorometric chemosensor based on imidazo[4,5-b]phenazine-2-thione for ultrasensitive detection and separation of Hg2+ in aqueous solution

We synthesized and developed 1,3-dihydro-2H-imidazo[4,5-b]phenazine-2-thione as a ratiometric chemosensor for Hg2+ recognition in a DMSO/H2O (v/v = 9:1) binary solution. We rationally introduced the phenazine imidazole group as the fluorophore and the thione moiety as the recognition site to bind Hg2+. Interestingly, the chemosensor showed an ultrasensitive response to Hg2+, and the lowest limit of detection was 0.167 nM. In addition, it can also separate Hg2+ from aqueous solutions with excellent ingestion capacity, with an adsorption ratio of up to 96%. Furthermore, ion test strips based on chemosensors were fabricated for convenient and efficient detection of Hg2+.