A strategically designed fluorescent turn‐on chemodosimeter for selective detection of mercury (<scp>II</scp>) via dithioacetal deprotection reaction

Abstract Mercury (Hg 2+ ) is one of the toxic heavy metals and poses severe health risks and environmental pollution. Thus, we report on the strategic design and synthesis of a new fluorescent chemodosimeter, (Z)‐3‐(4‐(1,3‐dithian‐2‐yl)phenyl)‐2‐(naphthalen‐2‐yl)acrylonitrile ( DTNA ), for detecting Hg 2+ . In the presence of Hg 2+ , DTNA exhibited an intense cyan fluorescence turn‐on, showing a significant Stokes shift (150 nm), a high quantum yield (Ф F = 0.2721), and high selectivity with low interference from other metal ions. The Hg 2+ recognition mechanism of DTNA was demonstrated as dithioacetal deprotection through 1 H NMR titration, ESI‐MS, FT‐IR, and DFT calculation. In particular, test papers coated with DTNA were successfully applied for monitoring Hg 2+ , enabling on‐site detection.