A Novel Benzimidazole-π-Bridge-Dicyanoisophorone-Type Near-Infrared Fluorescent Probe for Rapid Monitoring of Hydrogen Sulfide Based on a Cascade Thiolysis Strategy

<title>Abstract</title> <p> Herein, we designed a dual DNP-caged near-infrared probe, <bold>N-Bu-DCIB-2DNP</bold> , by conjugating dicyanoisophorone (DCI) with an N-alkylated benzimidazole (B) through double vinylene linkers. This probe features two responsive sites—the DNP ether on the donor and the DNP-functionalized electron-deficient quaternary carbon on the DCI unit—to enable a cascade thiolysis strategy. The probe exhibits distinct dual-emission fluorescence signals at 610 nm and 745 nm with large Stokes shifts, and achieves a rapid response to H ₂ S within 6 min, with a detection limit as low as 51.48 nM. Furthermore, test strips loaded with <bold>N-Bu-DCIB-2DNP</bold> enable convenient visual detection of H ₂ S in spoiled food samples, and its applicability in real water samples has also been validated, demonstrating its promising practical utility. </p>