Epirus-yellow (EY): A dual naked-eye colorimetric and NIR fluorimetric chemosensor for the rapid, sensitive, and selective detection of Sn2.

We introduce the compound (E)-2-(2-(3,4-dihydroxystyryl)-4H-chromen-4-ylidene)malononitrile, termed Epirus-Yellow (EY), as the first dual mode optical sensor for the naked-eye colorimetric and near-infrared (NIR) fluorometric selective detection of Sn2+. Designed for point-of-care (POC) cellular imaging and food-safety monitoring, EY exhibits exceptional sensitivity for colorimetric (23.4 × 10-8mol/L) and NIR fluorimetric (25.7 × 10-8mol/L) sensing, with a near-instantaneous response and complete colorimetric transition within 400 s. 1D/2D119Sn,1H, and13C NMR, UV-Vis, FT-IR, thermogravimetric analysis, ICP-MS, and DFT calculations elucidated the underlying mechanism. DFT suggests EY's oxidation, forming a quinone that interacts with Sn(OH)₂ through hydrogen bonding, leading to fluorescence. EY's applicability was demonstrated through paper strip and office scanner-assisted color quantification, with a visual detection limit of 12.0 × 10-7mol/L. EY was successfully applied to the real-time estimation of Sn2+in food and water samples, underscoring its potential for on-site food safety monitoring. Finally, a smartphone-assisted analytical platform and mobile application (Epirus4Tin) were developed, enabling user-friendly, real-time, and digital quantification of Sn²⁺ in agro-food samples.