Simple turn-on fluorescent probe for ultrafast and highly selective detection of hydrogen sulfide in aqueous solutions

Abstract

5H-Benzimidazo[1,2-c]quinazoline-6-thione (BI–QT), was synthesized as a benzimidazole-based probe to detect H2S. BI–QT exhibits a fluorescent “turn-on” response in DMSO/H2O (9:1, HEPES 10 mM, pH 7.4) upon the addition of H2S. The BI–QT probe can determine micromolar (0–600 µM) H2S concentrations in aqueous systems, with a detection limit of 1.12 µM. Interestingly, BI–QT exhibited an ultrafast response to H2S, with maximum intensity achieved almost instantly when exposed to H2S. BI–QT is largely unaffected by pH and responds reliably over the wide 4–11 pH range, which highlights its applicability to various physiological scenarios. UV–vis, fluorescence, and 1H NMR spectroscopic analyses investigated the sensing mechanism. The practicality of the probe was demonstrated using water samples and living cells.