Electrophilicity Modulation for Sub‐ppm Visualization and Discrimination of EDA

Precise and timely recognition of hazardous chemical substances is of great significance for safeguarding human health, ecological environment, public security, etc., especially crucial for adopting appropriate disposition measures. Up to now, there remains a practical challenge to sensitively detect and differentiate organic amines with similar chemical structures with intuitive analysis outcomes. Here, a unique optical probe with two electrophilic recognition sites for rapid and ultra‐sensitive ratiometric fluorescence detection of ethylenediamine (EDA) is presented, while producing distinct fluorescence signals to its structural analog. The probe exhibits ppb/nmol level sensitivity to liquidous and gaseous EDA, specific recognition toward EDA without disturbance to up to 28 potential interferents, as well as rapid fluorescence response within 0.2 s. By further combining the portable sensing chip with the convolutional algorithm endowed with image processing, this work cracked the problem of precisely discriminating the target and non‐targets at extremely low concentrations. A novel sensing strategy based on a unique differentiated‐nucleophilic mechanism is established with a boosted response to trace EDA either in liquid or gas and a distinguishable response for its structure analog—N2H4. This design concept is displayed as a telescope with tiny nucleophilicity discrimination ability toward the yachts labeled with EDA or N2H4 shown as blue emission or quenched fluorescence, respectively.