Novel coumarin-based ratiometric bifunctional fluorescent probe mimicking a set-reset memorized device

A novel coumarin-based fluorescent sensor CHE, incorporating 2-hydrazinylbenzothiazole and coumarin aldehyde, has been developed that demonstrated a preferential detection of Hg²⁺ and Ag⁺ in presence of interferences. Compared to previously prevalent intensity-based fluorescent probes, CHE exhibited a ratiometric fluorescence response to Hg²⁺ and Ag⁺, and further accurately differentiated Hg²⁺ and Ag ⁺ using the differential extractive ability of EDTA when interacting with ion-CHE complexes. Sensing mechanism was investigated and elucidated. The chemosensor CHE was successfully applied to detect Hg²⁺ and Ag⁺ in six distinct samples with satisfactory results. Additionally, combinatorial logic circuits were constructed utilizing three distinct logic gates (NOT, OR, and INH) based on the sensor's differential output signals in response to Hg²⁺/Ag⁺ and other cations. Interestingly, utilizing the reversible and reproducible switching behavior of the EDTA interaction with Hg²⁺, a conceptual 'Write-Read-Erase-Read' memory function with multi-write capability was proposed, offering a novel perspective for molecular-based memory systems.