Synthesis and Application of Pyrene-Based Fluorescent Probe for the Continuous Detection of Cu²⁺ and Picric Acid

A novel pyrene-based fluorescent probe PYS was designed and synthesized for the sequential detection of Cu²⁺ and picric acid (PA) under identical experimental conditions. In ethanol-HEPES buffer (V/V = 8:2, pH = 7.4), Cu²⁺ was selectively detected by PYS through fluorescence enhancement with a binding constant of 7.5 × 10⁴ L/mol and a detection limit of 9.3 × 10^-8 mol/L, demonstrating high sensitivity and anti-interference capability. The resulting complex PYS-Cu²⁺ functioned as a probe for PA detection, exhibiting instantaneous response (2 s) and high selectivity superior to other nitroaromatic compounds. The quenching mechanism was attributed to synergistic static quenching and inner filter effects, achieving a PA detection limit of 8.7 × 10^-7 mol/L, significantly below the permissible PA concentration (0.5 mg/L) specified in China's Surface Water Environmental Quality Standard (GB 3838-2002). Furthermore, a molecular logic gate system was successfully implemented using Cu²⁺ and PA as chemical inputs, highlighting its potential for sensing applications.