Synthesis of 2Dfluorescent polyaniline derivatives as multifunctional fluorescent chemosensor

Polyaniline (PANI) has been widely studied and applied due to its easy‐to‐obtain raw materials, excellent electrochemical performance and high environmental stability. Here, we present a general synthetic strategy for preparing two‐dimensional (2D) fluorescent PANI derivatives. The double bonds are used as a conjugated spacer between benzene rings in PPED and PPBA. The work breaks through the limitation of PANI derivatives are non‐emissive in solutions. The fluorescence quantum yields (Фf) of PPED and PPBA are 2.5% and 1.5%, respectively. PPED and PPBA show highly selective and sensitive detection of iron ion (Fe3+), copper ion (Cu2+) and hydrochloric acid (HCl). It is worth noting that the detection limit of PPED for Fe3+is 35 nM. In addition, the theoretical study indicates that the introduction of double bonds in PPED and PPBA greatly enhances their conjugation extent. The results demonstrate that we provide a powerful method for the preparation of highly sensitive fluorescent chemosensors based on 2D PANI derivatives.