A ratiometric small-molecule fluorescent probe for the selective detection of hypochlorite by an oxidative cyclization reaction: application to commercial disinfectants and live cells

Abstract

A highly selective thiophene-thioimidazole hydrazine-based ratiometric chemodosimeter (TPBN) was designed and synthesized to detect hypochlorite (ClO⁻). The probe showed yellow fluorescence and exhibited ultra sensitivity towards hypochlorite (detection limit 8.74 nM) through the oxidative intramolecular cyclization process to give a blue fluorescent triazole product (TPBN-P). Additionally, the as-designed sensor displayed a fast response (80 s) to hypochlorite with excellent selectivity over other competing analytes. DFT calculations, ESI-MS, and ¹H NMR titration experiments supported the detection mechanism. The probe was a valuable and practical ratiometric sensor for test strips, commercial disinfectants, and water samples. The probe was successfully used in the bio-imaging of hypochlorite in human breast cancer cells due to its noteworthy photophysical characteristics and good cell permeability.