A dual-state emission triphenylamine-based polymer with donor–acceptor–donor structural arrangement: facile synthesis and efficient selective detection of TNT based on fluorescence “turn-off”

Abstract

A novel donor–acceptor–donor (D–A–D) polymer, named poly(triphenylamine sulfone) (PTPAS), incorporating a triphenylamine group as the donor and a sulfone group as the acceptor, has been designed and synthesized. PTPAS was efficiently prepared using readily available materials through a catalyst-free C–N coupling reaction, demonstrating its suitability for large-scale industrial production. PTPAS exhibited remarkable thermal performance and demonstrated dual-state emission (DSE) characteristics, with fluorescence quantum yields of 0.58 in tetrahydrofuran solution, 0.27 in 99% aqueous solution, and 0.09 in the solid state. Moreover, PTPAS displayed exceptional fluorescence detection capabilities for TNT, exhibiting a high Stern–Volmer quenching constant (K_SV) of 2.98 × 10⁵ M⁻¹, a low limit of detection (LOD) of 94 nM, and a rapid response time of 15 s. Crucially, PTPAS maintained excellent fluorescence performance and TNT detection characteristics across an exceptionally broad pH range from 1 to 13, showcasing its versatility. Additionally, PTPAS exhibited robust resistance to interference from cations, anions, and other nitro-based explosives.