Aggregation-induced emission active conjugated polymers containing fluorene and carbazole for detection of 2,4,6-trinitrophenol

The detection of trace nitroaromatic explosives has become one of the hottest research areas in the field of environmental pollution monitoring. Designing aggregation-induced emission (AIE) active molecules, with flexible structural modifications and high fluorescence quantum yields, as fluorescence sensing materials offers a promising strategy for detecting nitroaromatic compounds. Here, two tetraarylethylene-based conjugated polymers named PF-F and PF-Cz were synthesized via Suzuki cross-coupling polymerization using dibromo-substituted 9-methylenefluorene and dihexylfluorene diboronic acid or heptylcarbazole diboronic ester, respectively. These polymers exhibit distinct AIE characteristics, with fluorescence quantum yields enhanced by 187 and 72 times in THF/H₂O (1/9, V/V) compared to pure THF. Fluorescence sensing experiments based on PF-F and PF-Cz demonstrate high sensitivity toward 2,4,6-trinitrophenol (TNP). With PF-Cz in THF/H₂O (2/8, V/V), a Stern-Volmer quenching constant of 1.56 × 10⁵ M⁻¹ was obtained, while the limit of detection (LOD) reached 0.09 μM. Moreover, both polymers exhibited high selectivity and anti-interference performance when exposed to various nitro-compounds and prevalent ions during the detection of TNP. Furthermore, the spike/recovery experiments for TNP detection based on PF-F and PF-Cz in actual aqueous samples yield recoveries ranging from 97.40 % to 107.40 %. Statistical t-tests indicate that the observed detection values are not significantly different from the actual concentrations added, demonstrating the reliability and sensitivity of PF-F and PF-Cz for TNP detection in real water samples.