Benzothiadiazole‐ and BINOL ‐based chiral π ‐conjugated polymers for tracing nitroaromatic compounds

Abstract

Nitroaromatic compounds (NACs), particularly nitrophenol derivatives, pose significant threats to environmental safety and national security due to their high toxicity and explosive nature. In this study, two novel chiral π ‐conjugated polymers, poly(( S ) ‐ BINOL‐BT‐ alt ‐OF) and poly(( R ) ‐ BINOL‐BT‐ alt ‐OF), were successfully synthesized via aerobic Suzuki–Miyaura cross‐coupling polycondensation. These polymers possess a donor–acceptor architecture integrating twisted 1,1′‐bi‐2‐naphthol (BINOL) units, electron‐deficient benzothiadiazole, and fluorene moieties. The resulting polymers exhibited strong intramolecular charge transfer characteristics and pronounced solvatochromic effects in various organic solvents. Fluorescence quenching experiments showed high sensitivity toward trace‐level NACs, with quenching efficiencies exceeding 90% for 4‐nitrophenol (4‐NP). The Stern–Volmer constants ( K SV ) were determined to be 1.66 × 10 4 and 1.95 × 10 4  L mol −1 for the S ‐ and R ‐enantiomers, respectively, with a limit of detection as low as 14.08 and 11.99 μmol L −1 . Mechanistic investigations revealed an analyte‐dependent quenching mechanism, involving synergistic contributions from photoinduced electron transfer and the primary inner filter effect (Primary‐IFE) for picric acid, whereas strong Primary‐IFE appears to be a major contributing factor in the quenching of 4‐NP because of its pronounced absorption at the excitation wavelength. Furthermore, paper‐based sensors were developed to enable rapid and visual detection. This study confirms that these chiral polymers serve as sensitive and reliable platforms for the detection of nitrophenolic analytes in both solution and solid phases. © 2026 Society of Chemical Industry.