An AIE luminogen-based electropolymerized film: an ultrasensitive fluorescent probe for TNP and Fe3+ in water

Abstract

Porous organic polymers (POP) are potential materials for fluorescent sensors because of their extended π-conjugated framework and porous structure. However, poor processability and photofunctionality are the major limitations for their practical applications. Here, a highly emissive photofunctional POP film (polyPhTPECz) was constructed using a simple in situ electropolymerization (EP) method. A novel high-luminescence aggregation-induced emission (AIE) molecule (PhTPECz), composed of multiple AIE groups as the central “core” and eight carbazole electroactive “arms,” was used as an electroactive precursor. Two possible twist conformations of polyPhTPECz were speculated and the corresponding pore diameters calculated to be ∼1.2 and 2.9 nm, respectively. These polyPhTPECz EP films were excellent multifunctional and reusable luminescent sensors for 2,4,6-trinitrophenol (TNP) and Fe³⁺ in an aqueous medium. The obtained limit of detection (LOD) was 3.8 and 10.0 nM for sensing TNP and Fe³⁺, respectively. These films also showed sensitive detection for TNP vapor. The fluorescence-quenching mechanism for TNP was a combination of electron transfer and resonance energy transfer. These excellent properties were mainly attributed to the high fluorescence property and cross-linked porous texture of these polyPhTPECz films.